212 Mr, Faraday on the Mutual Action of Sulphuric Acid [S E p t# 



much carbonaceous matter. The following was ultimately 

 adopted. 



A quantity of per-oxide of copper was prepared by heating 

 copper-plates in au* and scaling them. A sufficient quantity of 

 pure muriatic and nitric acid was provided, and also a speci- 

 men of pure native carbonate of baryta. Seven grains of the salt 

 to be examined were then mixed with seven grams of the pulve- 

 rized carbonate of baryta, and afterwards with 312 grains of the 

 oxide of copper. The mixture being put into a glass tube, was 

 successively heated throughout its mass, the gas liberated being 

 passed through a mixture of baryta-water and solution of 

 muriate of baryta. It was found that no sulphurous or sulphuric 

 acid came off, or indeed sulphur in any state. The contents of the 

 tube were then dissolved in an excess of the nitric and muriatic 

 acids, above that required to take up all that was soluble ; and a 

 little solution of muriate of baryta was added for the sake of 

 greater certainty. A portion of sulphate of baryta remained 

 undissolved, equivalent to the sulphuric acid of the salt experi- 

 mented upon, with that contained accidentally in the oxide of 

 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 experiment ; 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 deter- 

 mined. This, deducted from the weight afforded in the first 

 experiments, gave the quantity produced from the sulphuric acid 

 actually existing in the salt. Experiments 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. Front'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 carbonic 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*689 grains of water, for every 10 grains 

 of salt decomposed. 



