Chemistry, OSS 
during the fermentation. When the decomposition takes place 
zvith the contact of air^ the starch produces much water, into 
which the atmospherical oxygen gas does not enter as a con- 
stituent principle. It is formed from the carbonic acid gas, 
the oxygen of which belongs to the atmospherical air. The 
starch deposites charcoal, which browns all the products of the 
operation. The weight of the dry residue is less than that of 
the soap employed. When the decomposition takes place with- 
out the contact of the ah\ the stai’ch produces no water, but dis- 
(cngages a small quantity of carbonic acid gas, and pure hydro- 
gen. It deposites no charcoal. The weight of the dry resi- 
due is equal to that of the soap employed. 
16. Plwsphoric Acid in Vegetables.^ — Mr Barry of Plough 
Court, London, has discovered, in the preparation of pharma- 
ceutical extracts by evaporation in vacuo ^ “ that all those vege- 
tables which are cultivated, seem to contain phosphoric salt in 
great abundance.” 
17. New Diffki'ential Thermometer.— Dx Howard has de- 
scribed in tlie Journal of the Boyal Institution a new differen- 
tial thermometer, which differs only from the thermoscope of 
Count Rumford, or the differential thermometer of Leslie, in 
having the bulb filled with the vapour of alcohol or ether in 
place of air. An instrument of this kind has been exhibited 
for many years by the eminent Professor of Chemistry in the 
University of Edinburgh, and for magnifying the effect of small 
degrees of heat. He found it, however, as Dr Howard will al- 
so do, to be entirely unfit for the purpose of measuring differ 
rences of temperature. The-same remarks apply to Mr Brand’s 
idea of converting it into a Photometer. 
18. Braconnof S'method of dying Wool, Silk ^ Cotton and Hemp^ 
a fine Mineral Yellow Colour. — ^The substance vdiicli M. Bra- 
connot recommends for this purpose is realgar, or the sulphuret 
of arsenic. Having mixed 1 part of sulphur, 2 parts of the 
white oxide of arsenic, and 5 parts of potash of commerce, melt 
them in a crucible at a heat near that of redness. The yellow 
mass thus obtained is to be dissolved in hot water, and the li- 
quor fdtered, to separate it from a sediment. It is then to be 
diluted V. ith water, and sulpliuiic acid poured upon it, of sudi 
