1)6 BerzeUuii's Experiments to determine the Composition [Feb. 



know that the bas'e which saturates that acid contains half of 

 that quantity of oxygen. The following is a comparison of the 

 (juantity of oxygen which we have found combined with 100 of 

 le;id : 



7*7218 carbonate of lead. 



7'7223 reduction by hydrogen. 



7-7228 ditto. 



7-7316 muriate of lead. 



7-7400 reduction by hydrogen. 



7-7448 nitrate of lead. 



We see then that 100 lead combine with more than 7-72 oxy- 

 gen, and with less than 7-75. Three of these numbers differ only 

 in the sixth figure, and two only in the seventh. All circum- 

 stances considered, 1 conceive t may admit as the medium of 

 the determinations which are entitled to the greatest confidence 

 7-725, as the true quantity of oxygen which can unite with 100 

 lead. On that supposition, oxide of lead is composed of 



Lead 92-829 100-000 



Oxygen 7-171 7-725 



Sulplimic Acid. 



It is known that in the neutral sulphates, the sulphuric acid 

 ♦•ontains three times as much oxygen as the base by which it is 

 neutralized. We have just determined the composition of oxide 

 of lead. From this it is easy to determine the composition of 

 sulphuric acid by observing how much lead is yielded by a given 

 weight of sulphate of lead. I dissolved lead in pure nitric acid 

 in a Florence flask, inclined in such a manner that the efferves- 

 cence could drive nothing out of the vessel. The liquid M'as 

 then poured into a platinum crucible of a known weight. Pure 

 dilute sulphuric acid was mixed with it. It was evaporated to 

 dryness, and the excess of sulphuric acid was driven off by 

 exposing it to a red heat. This experiment appears very simple, 

 but it is of very difficult execution, in consequence of the weight 

 of the precipitate, which occasions portions of it to be driven out 

 of the vessel if the temperature be raised a little above 212*^. 1 

 made four experiments, and employed 10 grammes of lead each 

 time. They furnished the following results : 



First 14-6380 of sulphate of lead. 



Second 14-6400 



Third 14-6440 



Fourth 14-6458 



Among these experiments, the first differs in the fourth figure; 

 but the others ditier only in the sixth. 1 conceive that 1 may 

 choose the result of the third experiment ; that is to say, 14-644, 

 as nearest the truth. In this quantity of sulphate there is 

 10-7725 of oxide of lead and 3-8715 of sulphuric acid, the 



