SCIENTIFIC SUMMARY. 
391 
quantity of carbonate of magnesia is placed in it. The iodide is now 
mixed with eight times its weight of cyanide of potassium, and introduced 
into the tube ; next, a layer of the mixture of cyanide and lime is added ; and, 
finally, the upper part is covered with carbonate of magnesia. The tube 
is drawn out in the usual manner, and made to dip into water, when, 
heat being applied, the mercury distils over. Of the other means which 
may be employed in the decomposition of iodide of mercury, we may 
mention those of metallic zinc and protochloride of tin ; the former com- 
pletely decomposes the iodide, the iodine combining with the zinc ; the 
latter also reduces the metal, but rather incompletely. — Poggendorf’s 
Annaleil , chap, xviii., and Chemical News , February 27th. 
A New Form of Gunpowder has been devised by Messrs. Hall and 
Wells, of Worcester. It consists of 47 parts of chlorate of potash, 38 
parts of ferro-cyanide of potassum, and 5 parts of sulphur. The ingre- 
dients are first separately reduced to powder by grinding upon suitable 
slabs, then they are mixed together, water being used till they form a 
sort of paste. When the mixture has become dry, about ten parts of 
caoutchouc are added. The compound is then complete. One of its advan- 
tages is, that it may be so moulded that the entire charge shall con- 
stitute a solid mass, 'thus affording great facilities to the manufacture of 
cartridges. 
The Proportion of Ether in Brandy and Vinegar. — Mr. Berthelot, who 
has already estimated the percentage of ether in wine, now gives his 
attention to the substances which are derived from wines, or their principles ; 
to brandy, which is obtained by distillation ; and vinegar, which is a pro- 
duct of oxydation. Brandy contains the following materials 
1. Water. 
2. Ordinary alcohol, and some traces of Amylic, and other alcohols. 
3. Some of the volatile acids of wine (acetic, Butyric succinic ? &c.), 
traces of which only present themselves in ordinary wine, and most 
which remain in the case of brandy, in the undistilled residue. 
Besides these, there are empyreumatic acids in small proportions. 
4. The more volatile ether of wine (Acetic, Formic?). The pro- 
portion of these in wines is small, and distillation is too rapid to 
alter them to any great extent. 
5. Various volatile principles proceeding from the wine, or from the 
fermented liquor ; such, for example, as the essential oils, aldehydes, 
&c., empyreumatic products, and certain substances abstracted from 
the casks. 
In the preparation of vinegar, a large quantity of the alcohol is con- 
verted into acetic acid, and another portion is completely oxydised. If 
all the alcohol disappears no ethers will be found ; generally speaking, 
however, there remain slight traces of alcohol, and consequently of ethers 
also, whether these ethers pre-existed in the wine, or were developed at 
the moment of oxydation by the influence of nascent acetic acid, or at a 
later period by reason of the liquid being kept by for a long while. 
These ethers consist chiefly of the acetic form, because the acid of this 
series predominates. There can be no doubt that ethers give much of their 
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