1817.] during the Year 1816. 4} 
solution is evaporated to dryness, and the dry mass digested in 
alcohol. The alcoholic solution is treated in the same manner, and 
the dry residue is digested in ether. The ether, when evaporated, 
leaves a syrupy mass of a light wine colour. This mass, being dis- 
solved in alcohol, and the solution diluted with water, lets fall some 
resin. It consists now of the new acid, combined with a very little 
potash and lime. To obtain it in a state of purity, precipitate it 
with acetate of lead, and separate the oxide of lead by means of the 
requisite quantity of sulphuric acid. The acid thus prepared pos- 
sesses the following properties :— 
It may be crystallized. It has a light wine-yellow colour. Its 
taste is acid; and it dissolves in water, alcohol, and ether. It 
throws down lead and mercury white, but occasions no precipitate 
when poured into lime-water, nitrate of silver, or nitrate of barytes. 
It precipitates the oxides of iron white. Its combinations with lime, 
soda, and potash, are deliquescent, and soluble in alcohol. (Schweig- 
ger’s Journal, xv. 110.) 
8. Quantity of Carbonic Acid in the Atmosphere.—M. Theodore 
dé Saussure has lately published the result of a number of experi- 
ments to determine the relative proportion of carbonic acid in the 
atmospbeie during summer and winter. His method was to fill a 
large glass globe with the air to be examined, and to put into it 
a quantity of barytes-water. The carbonic acid in the air was deter- 
mined by the quantity of carbonate of barytes formed. ‘The fol- 
lowing tables exhibit his results :— 
In winter 10000 parts of air in volume gave 
~ Jan. 31, 1809, Temp. 23°, 4°57 parts of carbonic acid. 
2, 1811, 20:3, 4:66 
7, 1812, 34, 5°14 
Or the mean gives 4°79 parts of carbonic acid gas in 10000 measures 
of air. 
10000 parts of the same air in weight contain 7°28 parts of car- 
bonic acid gas. 
In summer 10000 measures of air gave 
Aug. 20, 1810, Temp. of 71°6°, 7°79 parts of carbonic acid gas. 
July 27, 1811, “16, 647 
15, 1815, 84:2, 713 
Or the mean gives 7°13 parts of carbonic acid gas in 10CO0 measures 
of air. 
10000 parts by weight of the same air contain 10°53 parts of 
carbonic acid gas. (Ann. de Chim, et Phys. ii, 199.) 
XII. SALTS. 
1. Sulphate of Manganese.—M. Brandenburg, apothecary at 
Polotzk, has published a set of experiments pointing out the method 
of preparing a pure sulphate of manganese from the common black 
oxide of manganese of commerce. 1 may just state his last process, 
which was perfectly successful, Four parts of finely flawed 
