SCIENTIFIC SUMMARY. 
433 
caused by the introduction of Anguillula stercorcdis and dysenterica, Ankly- 
stoma dysenterica, &c. into the intestinal canal by means of polluted water, 
may be avoided by dissolving alum in the water, although this is, of course, 
a less desirable method than that of boiling the water. The treatment with 
alum has, it is said, been successfully used by the natives of Annam from 
early times ; while for several years it has completely protected the French 
troops in Cochin China from this dreadful scourge. — The Chemical News , 
1878, xxxviii. 24. 
An interesting resume of the present state of our knowledge of the 
synthetical processes which are in operation in the bodies of animals has just 
been published by E. Baumann. It is entitled : u Ueber die synthetischen 
Processe im Thierkorper” (Berlin: Hirschwald, 1878). 
Magnesium Nitride. — Mallet obtains this compound by burning the metal 
in a limited supply of air. The band of magnesium when ignited is to be held 
well down in a porcelain crucible. If filings of the metal be used the same 
result is obtained, and with far greater completeness. The residue has a 
well-marked greenish-yellow colour, and evolves abundance of ammonia 
when moistened with water or a solution of a caustic alkali. When only a 
few drops of liquid are added the heat evolved is sometimes so great as to 
ignite a portion of the mass, and much of the powder is scattered by the 
escaping ammonia and aqueous vapour. In three analytical estimations of 
the results of the reaction it was found that 23*5, 27 ’5, and 24-8 per cent, of 
nitride were respectively formed. — The Chemical News , 1878, xxxviii. p. 39. 
The Dissociation of Sulphides. — The hydrates of metallic sulphides are 
decomposed by water when boiling, as well as at lower temperatures, sul- 
phuretted hydrogen being evolved and a metallic oxide formed. This is true 
of the majority of the sulphides, those of copper, bismuth, and mercur^ 
proving exceptions. Arsenic trisulphide is dissociated at the boiling-point 
into hydrogen sulphide and arsenious acid. De Clermont and Frommel have 
devised a method for the separation of arsenic from metallic sulphides which 
is based on this reaction. The mixed sulphides are to be suspended in water 
and boiled. The dissociation is soon complete. If the mixture weigh 
5 to 6 eg. the liquid should be boiled from twenty to twenty-five minutes. 
All remaining sulphides give insoluble oxides, which can readily be separated 
from the soluble arsenious acid. — Bull. Soc. Chim., Paris, 1878, xxix. p. 290. 
The Solubility of Bottle-glass. — Macagno has determined the degree of 
solubility in water of a number of specimens of bottle-glass derived from 
different sources, and ascertained in each case “ the corrosion degree ” of a 
boiling solution of potassium bitartrate. He finds that the chemical com- 
position of bottle-glass is hardly a correct indication of its quality. The 
amount of alkali or lime does not express the resisting power of the glass to 
water or acids. While the French glass is of very superior quality, the 
Rhenish, Madeira, Malaga, and Xeres bottles appear to have a very inferior 
composition. In order of colour we must set deep green in the first rank, 
in the second the white and common green, then the clear green, next 
the red-brown, while the worst are the yellow-brown, which must be re- 
garded as likely to contaminate ordinary wines containing much potassium 
bitartrate. In the case of the deep green glass of a Burgundy bottle the 
corrosion degree was 1*275; white glass, used for Rhenish, Bordeaux, and 
NEW SERIES, YOL. II. NO. VIII. F F 
