446 PROF. ROSE ON A NEW COMBINATION OF THE 



oxide of lead, I evaporated the whole to dryness, and heated the mass 

 to redness. I obtained from 1*613 grammes of the compound, treated 

 with fuming nitric acid and mixed with 10'739 grammes oxide of lead, 

 a mass which after being heated weighed 12*238 grammes, and which 

 contained therefore 1*499 grammes of sulphuric acid, or 92*93 per cent. 

 This experiment proves that the loss cannot be due to any formation 

 of hyposulphuric acid. 



The result of experiments in which I endeavoured to oxidize the 

 sulphurous acid by solutions of gold were much more uncertain. 

 For this purpose I employed a carefully prepared solution of the triple 

 salt, the chloride of gold, and sodium. The compound was brought 

 into contact with this in the same manner as in the former experi- 

 ments with nitric acid. The mixture was submitted, out of contact 

 with the air, to a moderate heat for about twenty-four hours. Two 

 experiments, conducted with equal care, gave however such widely 

 differing results, that it was impossible for me to explain the cause of 

 the great dissimilarity : for from 1*259 grammes of the compound I ob- 

 tained in one experiment only 0*058 of a gramme of metallic gold ; 

 whilst in a second experiment I obtained, from a much smaller quan- 

 tity of the compound, out of 0*667 of a gramme, more gold, namely 

 0*196 of a gramme. 



The estimating of the sulplmric acid in the compound gave much 

 more satisfactory results ; I was obliged to be contented with these, and 

 to estimate the quantity of sulphurous acid by the loss sustained. The 

 determination was effected in the following manner : a quantity of the 

 compound, weighed in a small glass bottle with a stopper, was put into 

 a larger bottle, which could also be closed by a glass stopper : this 

 contained a solution of chloride of barium, to which free muriatic acid 

 was added. As soon as the little bottle was introduced, the larger one 

 was closed ; and by shaking the vessel, the stopper of the little bottle, 

 which was merely loosely fixed, was thrown off, so that the compound 

 might mix with the solution of chloride of barium ; — an exceedingly 

 violent but not dangerous action ensued. 



After the sulphate of baryta was deposited, the liquid was quickly 

 filtered out of contact with the air, and its weight determined. An 

 addition of muriatic acid to the solution of chloride of barium is quite 

 necessary, because otherwise the sulphate of baryta cannot easily be 

 filtered, but passes milky through the filler. 



I have analysed four different portions, prepared at different times, in 

 this manner, and have obtained results which, though they agree much 

 less than those of less easily decomposable substances, yet on account 

 of the great decomposability and volatility of the compound, and there- 

 fore the difiiculty of freeing it from uncombined sulphuric or sulphur- 

 ous acid, agree more nearly than I expected. 



