268 
POPULAR SCIEHCE REVIEW. 
The Potato Disease. — Dr. de Barv, of Freibourg, has recently published 
a pamphlet containing an epitome of all that is known regarding the 
potato disease, and gives the results of his observations. He finds the 
theory of its being due to a parasitical growth to be correct. A seed or 
spore of the parasite, when placed in the leaf, he says, will penetrate the 
tissue in twelve hours, and in sixteen hours it bursts through the leaf, and 
is ready to reproduce itself at the rate of 19,G20 zoospores for every square 
line of its surface. 
URE CHEMISTRY. — Among the various matters of scientific interest, 
we may notice the experiments of M. Robinet, with reference to the 
purity of ice. It appears that water is rendered almost as pure by con- 
gelation as by distillation ; the calcareous and magnesian salts being 
forced out, in the act of freezing, as completely as the more soluble salts. 
He states that frozen water may be used for most chemical purposes 
in place of distilled water. Dr. RiidorfF has found that when a saline 
solution has frozen to such an extent that there is not sufficient water 
remaining to hold the salt in solution, it crystallizes. 
A new method of preparing hyposulphuric acid has been described 
by Gelis ; it consists in acting on sulphurous acid with hydrated peroxide 
of iron; the peroxide is suspended in water and sulphurous acid-gas 
passed into the solution where a compound of sulphurous acid and peroxide 
of iron is formed, which decomposes in a short time into hjqmsulphate 
and sulphite of protoxide of iron. 
Mendius has found that when the nitrites are exposed to nascent hydro- 
gen, a transformation takes place, and an amine base of the next higher 
homologous alcohol formed ; the method of proceeding was to act on a 
mixture of the nitrite with sulphuric acid by metallic zincs ; by this 
method hydrocyanic acid, acetonitrile, butyolonitrile, and benzonitrile, 
were transformed into methylamine, ethylamine, amylamine, and a new 
base of the composition, C,H 9 N. 
The conversion of aldehyd into alcohol by means of nascent hydrogen 
has been accomplished by Wurtz. To effect the change, all that is neces- 
sary is to expose a dilute solution of aldehyd in water to the action of an 
amalgam of sodium, when part of the aldehyd becomes resinified and the 
other part combines with hydrogen, to form a body possessing all the 
properties of ordinary alcohol. 
This process of transformation of organic bodies by the introduction of 
nascent hydrogen seems to be of general application, for Linneman has 
changed sugar into mannite, by acting with sodium amalgam on cane 
sugar, which has been changed to grape sugar by sulphuric acid ; and 
benzoic and valerianic aldehyds have been converted by Friedel into 
benzoic and valerianic alcohols. 
Mr. J. J. Andre has lately studied the action of chromic acid on 
vegetable alkaloids. He has found that definite crystallizable compounds 
CHEMISTRY. 
