576 



SCIENCE. 



cally executed prehensile motions. Such a stupid man- 

 ner of acting is incomplete contradiction to that which 

 is observed among animals that devote themselves to the 

 pursuit of other animals and feed on living prey; I pre- 

 sume, therefore, that the Aye-Aye feeds on vegetable 

 substances. I have often seen it, after having swallowed 

 a certain quantity of liquid food, devour a piece of bark." 



The Cheiromys, at the Botanical Garden, given by M. 

 Humblot and M. Archambault, act exactly like the one 

 which has been so conscientiously studied by Mr. Bart- 

 lett, jthe Superintendent of the Zoological Garden of 

 London. They sleep during the whole day, which is 

 very annoying to the visitors desirous of seeing these 

 strange animals, and, when the keeper tries to arouse them 

 from their sleep, they show their ill-humor by attempt- 

 ing to bite and by endeavoring to retreat to the most 

 obscure corner of their cage. 



In Madagascar, the Aye-Aye inhabits the large forests, 

 and are found jnot only in the western region, as Son- 

 nerat thought, but also on the southeastern side, where 

 it has been observed by M. Grandidier. According to 

 the natives, it builds a real nest, of a spherical form, in 

 which the female deposits and raises her young. This 

 assertion without doubt merits belief, since in 1877, M. 

 Soumage brought to France one of these nests, which 

 was built 'on the forked-head of two branches, and 

 which contained a female and her young. The walls of 

 this nest were formed of rolled leaves of the Ravenala 

 or Tree of the Traveler, covering an interweaving of 

 twigs ; it has on'one side a very narrow opening. 



The smallest of the other Lemurs — the Chirogales, the 

 Microcebes and the Lepilemurs — have, it appears, similar 

 habitats, and^also interweave, with twigs and leaves, a 

 home for their progeny, while the Makis, and all the 

 higher orders of Lemurs, build no nests, and carry their 

 young attached to their back or hung against their 

 breast. — Translated from La Nature. 



DETECTION OF OLEOMARGARINE * 

 By P. Casamajor. 



In the Moniteur Scientifiqueiox April, 1881, is an article 

 on Butter Analysis, in which are given the processes, used 

 at the Municipal Laboratory, attached to the Prefecture 

 of Police in Paris, for the detection of foreign fats in but- 

 ter. This is followed by an account of an areometric 

 method, used for the same purpose and based on the 

 difference of density between butter and the fats with low 

 melting point, extracted from tallow, which are made to 

 resemble genuine butter, and which are known under the 

 commercial name of Oleomargarine. 



The sale of Oleomargarine has become so extensive in 

 this country, that a purchaser of butter is never sure 

 whether he is getting true butter or its imitation. In 

 view of this fact, I have thought it useful to give a pro- 

 cess, based on the difference of specific gravity between 

 butter and oleomargarine, of such simplicity that it 

 can be easily applied by any person having rudimentary 

 ideas of manipulation. 



Processes of this character are those which can be used 

 with greatest efficiency to check adulterations. I have, 

 in previous communications, given such processes for the 

 detection of Starch Sugar mixed with Cane Sugar, and 

 for the detection of starch sugar syrup, mixed with sugar 

 house syrups. 



Although my concern is principally with the difference 

 of density between butter and oleomargarine, I propose 

 to very briefly call attention to the processes used at the 

 Municipal Laboratory of the Prefecture of Police, as these 

 show important differences in chemical composition be- 

 tween true butter and its adulterant, which confirm the 

 difference in the specific gravity. Such an important 

 character as the specific gravity would not differ to any 



* (Read before the American Chemical Society Sept. 1881. ) 



marked extent, without a corresponding diversity in the 

 composition of the two substances. 



One process used at the Municipal Laboratory is the 

 following : the sample of butter to be tested is melted, 

 so as to separate water, salt etc., which are deposited, 

 and a certain amount of scum, which comes to the sur- 

 face. Of the clear melted fat, under the scum, about 3 

 or 4 grammes are taken and saponified by 1 or 2 gram- 

 mes of potassic hydrate. The fat and potassa should be 

 mixed with 50 C. C. of alcohol. In about 5 minutes the 

 saponification is complete, and the cautious addition of 

 water should not produce any turbidity. If any takes 

 place, the operation must be begun anew. The soap form- 

 ed is afterwards decomposed with weak sulphuric acid, 

 and the insoluble fat acids are collected and weighed. 

 The result of a great number of experiments is that in 

 butter the percentage of fat acids thus obtained is usually 

 86.5 to 87.5 per cent., and that sometimes, it is as high as 

 88 per cent. In animal fats from tallow the percentage 

 of insoluble fat acids is 95^. The difference 95^ —87X 

 =8 per-cent, is attributed to the absence in tallow of vola- 

 tile and soluble fat acids which exist in butter. 



Another process is given in which the result is obtain- 

 ed volumetrically, by estimating the quantity of potassa 

 used in saponifying the fat. One gramme of butter re- 

 quires 225 to 232.4 C. C. of potassa solution, while 1 gram- 

 me of tallow, or other animal fat of the same nature, re- 

 quires from 195 to 197 grammes of the same potassa solu- 

 tion. 



Mr. Charles Girard, director of the Municipal Labora- 

 tory, considers as adulterated any butter requiring, for 

 saponification, less than 221.5 C.C., of the potassa solu- 

 tion. In some unfavorable cases this volume may repre- 

 sent nearly 30 per cent, of foreign fat. 



The method for detecting the difference between but- 

 ter and oleomargarine by the difference of specific gravity, 

 is one proposed by Messrs. Leune and Harburet. 



The butter to be tested is first melted so as to separate 

 the pure fat from water, salt, etc. The clear melted fat 

 is placed in a cylinder, heated by the vapor escaping from 

 a water bath, kept boiling, but no part of the cylinder is 

 to be in the boiling water. I understand that by heating 

 in this way, the temperature of the melted fat remains at 

 about 93 C. To determine the density of this fat an areo- 

 meter is placed in it. This areometer is graduated in 

 such a way that, in butter, it will sink to the lowest mark 

 of the scale, while oleomargarine corresponds to the high- 

 est point in the graduation. The intervening space is 

 divided into ten equal parts, each one of which corresponds 

 to of oleomargarine, mixed with butter. More than 

 600 experiments made by Messrs Leune and Harburet 

 with artificial mixtures show that, within an approxima- 

 tion of ten per cent., the instrument gives correct results. 



Soon alter this areometrjc method was published, it was 

 announced that the difference of the specific gravities of 

 butter and of oleomargarine, was too slight to distinguish 

 the one from the other. As Messrs. Leune and Harburet 

 had not stated what the specific gravity of each was, it 

 was impossible to judge of the truth of this statement, 

 and it became interesting to ascertain the facts of the 

 case. The following process is the result of my attempts 

 to determine the specific gravities of butter and of oleo- 

 margarine. I chose in the first place to ascertain the 

 specific gravity of each at 15° C, which is the usual tem- 

 perature for such determinations. The process consisted 

 in finding for each a liquid in which, at 15 C, a portion 

 of butter or of oleomargarine, freed from impurities by 

 previous melting and containing no air bubbles, would 

 remain in equilibrium in any portion of the liquid, with- 

 out any tendency to rise to the top or sink to the bottom. 

 The readiest liquid for this purpose was a mixture of al- 

 cohol and water, as this is easily prepared and it has no 

 dissolving action on the fats to be tested. As the density 

 of the liquid in which a body remains in equilibrium is the 

 density of the body itself, the problem was narrowed down 



