110 
POPULAR SCIENCE REVIEW. 
It has also been pointed out by these experimenters that the odorous 
principle of milk may readily be extracted by means of bisulphide of carbon, 
which does not dissolve the butter, but extracts the perfume of the milk, 
which they say is sometimes agreeable, sometimes not, according to the nature 
of the niaterial upon which the animal has been fed. In reference to colour, 
they found that the butter of cow’s milk is always yellow, but that of goats, 
sheep, asses, and the human female, is invariably white. — Vide Comptes 
Renclus, August 8 and 27. 
How to detect Impurities in Alkaloids. — MM. de Vry and Alluard com- 
municated some interestmg facts relating to this question to a late meeting of 
the French Academy. Their experiments were principally made upon speci- 
mens of quinine, and consisted in the examination of polarized light, which 
had been allowed to traverse the crystals. On comparing in this way the 
best quinine of commerce with the pure alkaloid prepared by themselves, 
they found, as might have been anticipated, that the polariscope revealed the 
presence of impurities, when these were in too small proportions to be de- 
tected by chemical processes. The reason alleged for these inquiries is that 
MM. de Vry and Alluard had found M. Bouchardat’s detenninations to be 
erroneous. 
Cause of the Coagulation of Albumen. — Tliat this is rather a physical than 
a chemical process is the opinion of a rising Irish chemist, Mr. Emerson 
Eeynolds of Dublin. It is well known that albuminous liquids .containing 
a small amount of alkali are easily coagulated by heat ; but if the quantity of 
alkali be increased, a point is arrived at where its influence physically appears 
to be lost. “ If, then,” writes Mr. Eeynolds, “ we regard a solution of pure 
albumen as being in a state of unstable equilibrium, capable of being upset 
by very slight physical causes, the addition of a minute trace of alkali tends 
to throw the balance on the side of permanent solution, for then mere agita- 
tion or friction is not able to overcome the influence of the alkali ; but if we 
apply the more powerful physical agent (heat) the obstacle is easily surmounted, 
and the result is coagulation. Let us now go a step farther, and add a still 
larger proportion of alkali ; we then find that even the highest temperature 
to which the mixture can be brought is insufficient to produce coagulation, 
owing probably to the intensity of the physical agent being too low to over- 
come the affinity between the acid and base. If, however, a neutral salt, such 
as nitrate of potassium or sulphate of sodiiun, be added, the boiling point is 
raised, the "intensity of the physical force is increased proportionably, and 
the result again is coagulation.”- — Vide Dublin Quarterly Journal of 
Science, No. XV. 
The Preparation of A niline Green. — We believe we are correct in stating, 
that the first who observed the reaction which [produces this beautiful tint 
was M. Eusebe. He found that when he dissolved crystallized aniline red in 
a mixture of alcohol with sulphuric, hydrochloric, or other acid, and added 
a certain quantity of wood spirit, an exquisite violet hue was produced ; this 
quickly changed to blue, and then, on the addition of hyposulphite of soda, 
a lovely green colour was developed. This process, however, though important, 
as having orginated the discovery, has many serious disadvantages. The 
colour may readily be produced by the adoption of the following method : 
150 grammes of crystallized sulphate of rosaniline are dissolved in 450 grammes 
