SCIENTIFIC SUMMARY. 
425 
explored by Mr, A. H. Smee, who read a paper on it before tbe Chemical 
Society on one of the last evenings of the session. He found that, although 
milk taken from herds of cows exhibits great uniformity in composition, yet 
the milk from individual cows is liable to considerable variation ; moreover, it 
is possible for good average milk to be watered to a limited extent without 
detection. He observed, also, from a comparison of the milk from cows fed 
on ordinary meadow grass and on grass from a sewage farm, that in the 
latter case the milk went putrid after thirty-six hours, and the butter 
became rancid rapidly compared with that made from the milk of cows fed 
on ordinary meadow grass. These effects were more apparent in spring than 
in the latter part of the summer. On three or four occasions, also, he 
noticed that when the milk of cows fed on sewage grass was placed on a 
dialyser, the casein passed through the membrane, from which it would 
appear that the casein existed in these milks in a modified form. He then 
proceeded to notice the outbreaks of typhoid fever which had occurred at 
various places owing to sewage water having been used to cleanse the dairy 
utensils, or to reduce the quantity of rich milk to the lowest standard 
allowed by law, showing how important it was that there should be a 
supply of pure water to every dairy. Moreover, milk which had been 
exposed to sewage-gas from an untrapped drain, although on analysis it 
appeared to be unaltered in composition, yet when distilled at a low tem- 
perature (160° F.) it yielded a distillate which had a very offensive smell. 
It also caused intense headache, which was followed by diarrhoea. He also 
examined the milk of cows suffering from foot and mouth disease and from 
milk fever, and thought that the methods employed by Public Analysts 
were not sufficiently delicate to detect the slight physiological changes 
which may take place in so complex a fluid as milk. 
A Method of modifying the Explosiveness of Methyl-nitrate . — This sub- 
stance, which has caused the death of Dr. Chapman’s distinguished son, 
has been recently experimented on with a view to render it harmless. M. 
Girard, who has been employing it largely for the production of colours, 
has made some experiments with it with this view. He finds, for ex- 
ample, that methyl-nitrate, like nitro-glycerin, detonates by a blow ; a drop 
on blotting-paper producing, when placed on an anvil and struck with a 
hammer, an explosion quite as violent as nitro-glycerin. When mixed with 
pulverulent or porous substances, such as precipitated silica or infusorial 
earth, it yields dynamites fully as effective as those made with nitro- 
glycerin. By admixture with other liquids, however, such as methyl, 
ethyl, or amyl alcohol, acetone, benzol or toluol, Girard finds that it is no 
longer explosive. One part of methyl nitrate diluted with two or three 
parts of either of the liquids above named does not explode either on 
heating its vapour or by a blow. In such solutions, therefore, it is best 
kept for use. 
