158 Mr . Faraday on the mutual action of sulphuric acid 
copper acids, &c. This sulphate was collected, washed, dried 
and weighed. Similar quantities of the carbonate of baryta 
and oxide of copper were then dissolved in as much of the 
nitric and muriatic acids as was used in the former experi- 
ment ; and the washings and other operations being repeated 
exactly in the same way, the quantity of sulphate of baryta 
occasioned by the presence of sulphuric acid in the oxide, 
acids, &c. was determined. This, deducted from the weight 
afforded in the first experiments, gave the quantity produced 
from the sulphuric acid actually existing in the salt. Expe- 
riments so conducted gave very uniform results. The mean 
of many, indicated 8.9 grains of sulphate of baryta for 10 
grains of salt used, or 89 grains per cent, equivalent to 
30.17 of sulphuric acid for every 100 of salt decomposed. 
In the analytical experiments, relative to the quantity of 
carbon and hydrogen contained in the salt, a given weight 
of the substance being mixed with per-oxide of copper, was 
heated in a green glass tube. The apparatus used consisted 
of Mr. Cooper’s lamp furnace, with Dr. Prout’s mercurial 
trough ; and all the precautions that could be taken, and 
which are now well known, were adopted for the purpose of 
obtaining accurate results. When operated upon in this 
way, the only substances evolved from the salt, were car- 
bonic acid and water. As an instance of the results, 3.5 
grains of the salt afforded 11.74 cubic inches of carbonic acid 
gas, and 0.9 of a grain of water. The mean of several 
experiments gave 32.93 cubic inches of carbonic acid gas, 
and 2.589 grains of water, for every 10 grains of salt 
decomposed. 
On these data, 100 grains of the salt would yield 32 9.3 
