Imagens das páginas
PDF
ePub

as cattle food in the South of France. If the new industry is to succeed here it will have to be supported by the agricultural interests.

Some idea of the magnitude of the nut-oil industry is gained from the following figures:-The world's production of coco-nut and copra oil 19131914 is estimated at 377,000 tons, of which 300,000 tons were used in Europe. The total supply of hard vegetable fats (coco-nut and palm kernel oil) available for margarine is said to have been 240,000 tons in 1913, and perhaps 300,000 tons in 1914. Out of 347,000 tons of hard fat stated to be used for margarine in 1913, 204,000 tons were vegetable, and the quantity of vegetable fat used in 1914 may have amounted to 300,000 tons, i.e., the total visible supply. There is little wonder that there has been a great increase in the price of these oils, and that the tropical sources of palm tree oils are being widely exploited. Nearly all tropical countries report an increase in the area under coco-nuts, or an improvement in the methods of dealing with the existing trees, and in the machinery for making copra or extracting the oil, which is still very primitive and inadequate.

The nut oils resemble butter and differ from all other fats in containing a large proportion of fatty acids of low molecular weight. Butter contains acids from butyric acid upwards in the homologous acetic acid series; the chief constituent of nut oils is lauric acid. Few of the remaining oils of commerce contain acids lower in the series than palmitic acid.

In preparing vegetable fats for the market the all-important consideration is the careful selection of the raw materials. The oil is worked as fresh as possible, so that the best results are obtained when the seed is pressed in this country. It should be understood that the refining process involves no treatment with chemicals except the agitation with weak alkali to remove the fatty acids present.

The importance of fats in the dietary requires no emphasis; on the other hand, it is questionable whether all fats have the same value as food materials. Fats, being glycerides, are decomposed in their passage through the alimentary system into glycerol and fatty acids. The decomposition is effected through the agency of an enzyme, lipase, so that the digestibility of the fat depends on the rate at which it is attacked by the enzyme. The fat has to be brought into a suitable state of emulsification before the enzyme can act on it; and though the factors controlling this state are still somewhat obscure, it is above all important that the fat should melt readily at the temperature of the body. Hence the comparative digestibility of a fat is in the first place based on its melting-point. Stearine is badly digested, liquid oleine is readily digested. The addition of sufficient oleine to stearine so as to reduce the melting-point of the mixture renders the stearine also digestible. Consequently the all-important point which margarine makers keep in view is the melting-point of their product in relation to the body temperature; if this is correct the material

may contain some ingredients of a considerably higher melting-point.

It is of interest to note in this connection that vegetable fats are composed to a great extent of mixed tri-glycerides-that is, the glyceride contains more than one fatty acid in its molecule, whereas normally one molecule of glycerol is coupled with three molecules of the same fatty acid. Experience teaches that the melting-point of the fat will be greatest when these are all the same. The melting-point of the fat is further influenced by the fact that it consists of a number of different glycerides, both simple and mixed. Since mixing of fats has the result of altering the relative proportions of these it is evident that the final melting-point of a mixture cannot be predicted on theoretical grounds, and it is agreed that butter substitutes of suitable melting-point are as digestible as butter.

It is customary to measure approximately the nutritive function of a food by its energy value in calories per pound, .but modern research has shown this method to be inaccurate in two respects. In the first place it ignores the quality of the food; secondly, it neglects the presence in traces of the vitamines.

It has been found by experimenting with isolated food substances that diets otherwise sufficient in energy value fail to maintain growth and health unless they contain certain substances hitherto unrecognised, but which have been named vitamines. The work in this field is of recent date, and is vitiated by the usual errors accompanying premature publication-indeed, much of it has been recalled already, but it would appear that the vitamines are of lipoid nature. They are present in butter, but not in the refined fats which are used for butter substitutes. How far this difference is of importance it is difficult to say; probably sufficient vitamines are present in the rest of the dietary to enable them to be dispensed with in the fat.

The question of quality is of more importance, though it has hitherto largely escaped attention. The individual fatty acids probably differ in their value in somewhat the same way as the different amino-acid constituents of the proteins have been shown to do, though to a less extent. The lower fatty acids in butter are perhaps specially important in making it of more value than olive oil, which is composed mainly of oleic acid, or than fats composed entirely of palmitic and stearic acids. Nut oils, however, resemble butter in containing a proportion of the lower acids, and hence their use in butter substitutes is entirely rational from the point of view of nutritive value. In the foregoing the nature and preparation of materials available for use as butter substitutes have been indicated and their food value discussed. When it is remembered that the new industry is under rigid scientific control and conducted with a cleanliness mostly unknown in the butter industry, and, moreover, that it has made edible. fats available for the masses at half the price of butter, it must be proclaimed as yet another of the achievements of science in the service of man.

IT

THROUGH THE INTERIOR OF BRAZIL.1 T is an instance of rare good fortune for a man who delights in the life of a field-naturalist to be offered the honorary leadership of a scientific expedition, by a Government not his own, through a large stretch of unexplored tropical country, to embark upon an unknown river, piecing it together with others but hazily known, and to have the now complete large river called after himself. However unique such a stroke of luck, the necessary premises are equally rare in their combination of an ardent naturalist, keen sportsman, vigorous experienced traveller, leader of men as a former president of the great American Republic, and attractive, versatile writer !

The idea of a journey through the interior of Brazil had been suggested to Colonel Roosevelt by Father Zahm, a missionary. It took shape when he was invited, through the Governments of Argentina and Brazil, to deliver addresses to their various learned societies, and he decided to combine this visit with a collecting tour for the American Museum of Natural History. When at Rio, the Government offered him the conjoint leadership of a scientific expedition which the Telegraph Commission was going to make through the very heart of the continent, down the now famous Rio Duvida. The geographical problem may be illustrated as follows. Let my right arm represent the lower Amazon river, the thumb the Tapajoz, the middle finger the Madeira, the index its most eastern and last tributary. The first joint of the index finger was known as the lower Aripuanan, composed of the upper Aripuanan and

experience, as the handy man, and Father Zahm. Well found and equipped they left Asuncion on December 9, 1913, and ascended the Paraguay up to the headquarters of the Telegraph Commission, about 15° S. There is, extending towards northwest, the Serra Geral, the divide between the La Plata basin and that of the Amazon, but recently explored, with its numerous streams, by the Commission. Here the collections hitherto made were sent back, with Father Zahm. Fiala, with a few companions, was sent down a tributary of the Tapajoz. They got through, down this river, having lost everything but their lives. On February 3, 1914, the main party continued the journey with mule packs and ox carts, still following the telegraph and crossing many streams. Miller, with a small party, went on, to descend the Gyparana, etc., for Manaos, which turned out a most successful collecting trip. The main party combined with the Brazilian members: Colonel

[graphic]

FIG. 1.-One of the canoes. From "Through the Brazilian Wilderness."

the Castanho river; this, the second joint, was known to rubber men only. The third joint represents the Duvida. A few miles of this river had been discovered by the Telegraph Commission in 1909, and there was a long gap between it and the Castanho of unknown extent. Moreover, it was not unlikely that the Duvida was, after all, but a tributary of the Gyparana, an affluent of the Madeira, already well known; and it was just possible that the river of Doubt turned sharp to the east and fell into the Tapajoz. However, the authorities ordered a party to ascend the Aripuanan up to the mouth of the Castanho and there to wait for the explorers.

The American party consisted of the Colonel and his son, Messrs. Miller and Cherrie as experienced zoological collectors, Fiala, of Arctic

1 "Through the Brazilian Wilderness." By Theodore Roosevelt. Pp. xiv+374 (London: John Murray, 1914.) Price 18s. net.

Rondon, chief of the Commission, Lieut. Lyra, and Dr. Oliveira.

They embarked upon the Duvida on February 27 in seven dug-outs, with sixteen paddlers, twentytwo men all told, with provisions for fifty days, hoping to reach the Madeira within six weeks. The starting point was at 12° 1' S.; 60° 15' W. All went well until March 3, when at 11° 44' S. the first rapids were encountered. Then began the misery of portaging, carrying the loads and dragging the clumsy dug-outs through or past rapid after rapid, amidst dense forest, in the rainy season, with a plague of biting ants, flies, and termites which devoured their outfit. Nevertheless, the Colonel was reading poetry in head-net and gauntlets." On one occasion it took them three full days to negotiate one mile of rapids. By March 25 they had descended only 160 kilometres of the winding river, had lost four canoes,

[ocr errors]

including a new one made on the way, with provisions, ropes and pulleys, and one of the crew. A dog was killed by unseen Indians, the outfit had to be cut down to the utmost, and the sadly shrunk provisions had to be supplemented by palm-tops, fish, nuts, and an occasional monkey or wood-fowl. Illness, and a case of murder case of murder amongst the crew added to the depression.

Things were at their worst, when the river became more manageable, and when, on April 15, they came to the first house of rubber men, who informed them that they were on the Castanho river, about fifteen days from its confluence with the Aripuanan. This happened at 10° 24'. Henceforth, they enjoyed every help, and on April 26 they made the mouth of the Castanho, at 7° 34', where Lieut. Lyra was encamped, waiting for the explorers. On the last of the month all the parties met at Manaos. By discovery and piecing together they had put on the map a new river;

varied aspects. He kept his eyes open, and, with a pleasant style, shows his delight whenever he comes across some creature he had not seen before. At the outset, at a visit to the serumtherapeutic institute at São Paulo, we get a lecture on snakes and their poison, and he assisted in experimenting with the mussurana, a snakeeating, harmless, immune snake. But we are not told its scientific name (Rhachidelus brazili, Blgr.) one of many similar regrettable instances in his book. The technical names are, of course, the bane of the vast majority of readers. Vernacular names are preferable, but there is a limit, and two words in brackets would satisfy everybody.

He speculates whether the white-tailed deer is an immigrant from the Northern Continent, arguing from the season of the shedding of its antlers. The marsh-deer, with its advertising red coloration, is just as successful as

the black- and the whitetailed deer, whichR are found in the same neighbourhood. "Evidently it is of no survival consequence whether the running deer displays a white or a black flag." Pumas, ocelots, jaguars, spotted or quite black, were killed in the same locality. "In many cases coloration is of no consequence whatever; instead of being a survival factor, it becomes negligible through the other factors of overwhelming importance, as habits, cleverness, etc." Thus speaks the experienced sportsman on one of his favourite subjects. On another occasion he is puzzled why the jaguar should climb trees to escape dogs, "for ages have passed since there were in its habitat any natural foes from which it needed to seek safety in trees." Such and similar arguments usually do not come to much, but they are samples of scores that he did not go out merely to bag his jaguar. Birds, beasts, coral snakes, and piranha fishes, toads and ants, and primitive natives, he has something to say about, not always new, but to the point.

[graphic]

FIG. 2.-Rapids of the Duvida. From "Through the Brazilian Wilderness.'

=

allowing for unknown headwaters and the windings of its whole, rather straight course, amounting to a total length of 1000 kilometres, not miles. This river enjoys now an abundance of names. Duvida + Castanho + Lower Aripuanan Rio Roosevelt, as proclaimed officially by Colonel Rondon, but in one of the two maps of the book it is called Rio Teodoro. It was a very successful expedition, its object having been obtained in the way it had been planned.

The various collections amounted to the great number of 3000 birds and mammals. Concerning the description of the country, its people, fauna, and flora, the narrative divides itself naturally into two parts. Soon after reaching the Duvida the pleasant occupation of collecting and observing had to give way to dangerous toil, the ways and means of getting through at all. Up to the divide Colonel Roosevelt had a glorious opportunity of indulging in the study of nature in her most

To

Every naturalist will agree with him that the mere collecting for museums is all very well, to a certain extent, a necessary evil, but what is now wanted are observations of the economy of the creatures, as parts of their environment. secure such information, send out educated men who can give a readable account of their experiences. With exception of the two very sketchy maps most of the fifty illustrations are beautiful and characteristic. H. G.

THE "ORIGINAL" SPECIFIC GRAVITY OF BEER.

THEM

'HE December (1914) issue of the Journal of the Institute of Brewing is an important number of this publication, and of more than merely technical interest. It contains a series of reports and memoranda upon the subject of the determination of the "original" specific gravity of beer, and the results of the work described have now, by the Finance Act of 1914, been legalised as the basis for checking or determining the charge of duty upon this beverage. The main reports are contributed jointly by Sir Edward Thorpe and Dr. H. T. Brown, and the latter author supplements them by interesting

studies of both the historical and the scientific aspect of the question.

This,

a

Beer is taxed as being an alcoholic beverage, and it is popularly supposed to pay duty according to the amount of alcohol it contains. however, is not strictly the case. The basis of taxation is not the actual quantity of alcohol in the beer, but the specific gravity of the unfermented wort, which may be regarded as measure of the quantity of alcohol potentially producible. Essentially, the wort of beer is a solution of various sugars-maltose, dextrose, cane sugar, and invert sugar-either arising from the malt and grain used, or directly added as such. The proportion of sugars varies considerably, according to the kind of product desired. In wort for producing strong ale, for instance, there may be twice as much sugar as in that destined for ordinary table beer. But, in the main, the proportion of sugar determines the specific gravity of the unfermented wort, and the specific gravity is therefore made the basis of the charge of duty levied on the beer. A brewer is thus left at liberty to ferment his wort as much or as little as he likes, and to produce a stronger or a weaker, a heavier or a lighter beverage, as his fancy dictates or his customers prefer.

As soon as fermentation commences, the specific gravity of the wort begins to alter, and in general to decrease. This is so for two reasons.

First,

the destruction of sugar by fermentation removes solid matter from solution; and secondly, the alcohol produced is specifically lighter than the wort. Hence, unless the specific gravity is determined before fermentation has commenced it is useless as the basis for the correct assessment of duty. It is impracticable, however, to have a revenue officer in attendance in all cases to take the specific gravity of the wort before fermentation begins; moreover, it often happens that the "collection" of the wort extends over several hours, during which time the first portions may have been in contact with yeast, and fermented to an appreciable degree, before the last portions have been added. Even were this not so, other difficulties arise. A large quantity of beer is exported, and the exporter is entitled to a "drawback" or rebate equivalent to the duty originally charged upon the unfermented wort from which the beer was made. Hence it is necessary to

[blocks in formation]

that 100 parts of this sugar yield theoretically 538 parts of alcohol. 538 parts of alcohol. Hence by determining the quantity of alcohol in a given specimen of wort or beer, we find the equivalent amount of sugar destroyed; and from the known density of solutions of maltose we can thus deduce the corresponding loss of specific gravity. Adding the number denoting this loss to the specific gravity of the residual wort or beer freed from alcohol, we can, theoretically, obtain the "original" specific gravity of the wort, i.e., the gravity before fermentation had commenced.

In practice, however, this calculation is not sufficiently accurate. As Pasteur long ago showed in his studies of fermentation, a part of the sugar Moredestroyed is not converted into alcohol. over, different classes of sugars yield different percentages of alcohol. Again, the introduction of yeast complicates the matter, since part of the solid matter of the wort is used up in sustaining the growth of the yeast, and a sensible quantity of alcohol may be added as such with the yeast itself. These and other disturbing factors, small individually, together affect the result sufficiently to render the figures given by the simple theoretical method, as outlined above, only an approximation to what obtains in actual brewery operations.

We have, in fact, to fall back upon an empirical basis for the calculation of results sufficiently accurate to be used in practice. Starting with worts of known specific gravity, fermentations may be carried out, and from the examination of samples drawn as the process continues, it can be ascertained experimentally what is the actual loss of specific gravity consequent upon the production of known quantities of alcohol. Such experiments, in fact, have been made, and the results have been embodied in statutory tables for use in assessing the duty on beer.

Manifestly it is of much importance that these tables should be true and just. If inaccurate in one direction they are unfair to the public by reason of the loss of revenue entailed; if erroneous in the opposite sense they are unfair to the brewer.

[blocks in formation]

sented to the authorities in 1852, and published the same year in the Journal of the Chemical Society. For some time past it has been known that the table supplied with this report is less accurate than is desirable-not, it appears, from any inherent errors, but from having been based upon fermentations which differed in some respects from those obtaining in ordinary brewery practice. About six years ago, therefore, the Commissioners of Customs and Excise gave instructions for a revision of the table to be made. This was undertaken by Sir Edward Thorpe, who was at that time principal chemist of the Government Laboratory, conjointly with Dr. H. T. Brown, nominated on behalf of the brewing trade by the Council of the Institute of Brewing. The necessary experiments, which altogether extended over a period of about two years, comprised not only brewings made under laboratory conditions, but an extensive series of observations at representative breweries, in order to obtain data which should correspond fairly with the actual working conditions met with in modern brewing practice. In the result a table has been constructed which there is every reason to believe is trustworthy, and which has now been legally established for use in place of the former statutory table of Profs. Graham, Hofmann, and Redwood. As compared with the older table, its general effect is somewhat to increase the amount of duty chargeable.

Dr. Brown's special contribution is a valuable study of the scientific principles underlying the empirical method of determining original specific gravity. He shows that a reasoned or theoretical" process is quite possible-though not necessarily preferable if the data have been properly

established.

[ocr errors]

C. SIMMONDS.

ROLL-CALL OF BRITISH BIRDS.1

E have received from the British Ornitho

WE logists' Union the second and revised

edition of its "List of British Birds." It is an authoritative compilation which does credit to the zeal and carefulness of the editorial committee. While the task was only accomplished by division of labour, the whole has been revised by the entire committee, who consider themselves jointly responsible, although many disputed points have been decided by the votes of the majority. The first edition, published in 1883, included 376 birds; the present edition has 475, quite apart from a long list of species the presence of which has been recorded, but not satisfactorily proved.

It is interesting to look into the composition of the list of 475 birds. In the first place, 188 are regular breeding birds, and 286 are non-breeding, and one (the great auk) is extinct. The list may be further sub-divided. Thus, there are 141 residents, including, of course, many that are partially migratory. In this category are included three introduced birds-the little owl, the pheasant, and the red-legged partridge, besides the 1 "A List of British Birds." Compiled by a Committee of the British Ornithologists' Union. Second and Revised Edition. Pp. xxii +430. (London: W. Wesley and Son, 1915.) Price 7s. 6d.

capercaillie, which was indigenous, but became extinct about 1760-70, and was re-introduced from Sweden in 1837-8. A second set is made up of 47 summer visitors, including a few which occasionally leave representatives with us in winter. The third set consists of 46 winter visitors; the fourth of 30 birds of passage; the fifth of 61 occasional visitors which have occurred on more than twenty occasions.

The largest category in the classification is that of rare visitors, which have been recorded on fewer than twenty occasions. This group numbers 149, which shows how diligent the search for the occurrence of rare birds has been in the British Islands. Under each bird we find a few references the etymology of the name, the distribution in the British Islands, and the general distribution. A long appendix is devoted to the birds which have been excluded because the evidence of their occurrence is not regarded by the committee as entirely satisfactory. satisfactory. Two others deal with questions of nomenclature. The members of the committee deserve the thanks of all ornithologists for the effectiveness with which they have done their work, which must have made heavy demands on their time and afforded abundant exercise for their judgment.

NOTES.

WE learn with much regret of the sudden death on March 23, through heart-failure, of Prof. Otto N. Witt, professor of chemical technology in the Technical High School at Charlottenburg.

DR. F. TAYLOR, consulting physician to Guy's Hospital, has been elected president of the Royal College of Physicians in succession to Sir Thomas Barlow.

THE fifth annual award of the Willard Gibbs Medal, founded by Mr. W. A. Converse, of Chicago, has been made, says Science, to Prof. A. A. Noyes, director of the research laboratory of physical chemistry, Massachusetts Institute of Technology.

A STRONG after-shock of the Avezzano earthquake of January 13 was felt in Rome on April 5, at 7.20 a.m. (6.20 G.M.T.). According to a report issued by the geodynamic observatory at Rome, the epicentre of the after-shock appears to have been close to Avezzano.

THE American Philosophical Society will meet at Philadelphia on April 22-24 for the reading and discussion of papers. The programme includes papers on many subjects of recent research in physical and natural science, and also a symposium on the earth : its figure, dimensions, and the constitution of its interior.

DR. J. SCOTT KELTIE, who has been secretary of the Royal Geographical Society since 1892, vacated that office at the end of last month, and has been succeeded by Mr. A. R. Hinks, who has been assistant secretary of the society since 1913. Dr. Keltie will not, however, entirely sever his official connection with the society, for he has undertaken to act with Mr. Hinks as joint-editor of the Geographical Journal for the next

two years.

« AnteriorContinuar »