344 On definite Vroportiom. 



C. Sulphate of the Protoxide of head. 



1.) I dissolved 30 gr. of pure lead in nitric acid, put the 

 solution ilito a platina crucible, with sulphuric acid in ex- 

 cess, dried it carefully, and ignited it. The sulphate of lead 

 weighed 43-9 gr. Consequently 100 parts of sulphuric 

 acid were saturated by 278-77 of the oxide, precisely as in 

 the former exjieriments. 



2.) Thirty grammes of pure protoxide of lead were dis- 

 solved in nitric acid, decomposed by an excess of sulphuric 

 acid, and dried and ignited in the platina crucible. The 

 dried protoxide weighed 40'77gr. ; so that 100 parts of 

 sulphuric acid had united v/ith 278-5.'j of the protoxide. 

 If I omitted to employ the sulphuric acid in excess, a part 

 of it was driven away at 'a high temperature, by the nitric 

 acid, and I obtained a mixture of the sulphate with the 

 simple protoxide. . 



3.) 1 dissolved 15 gr. of the protoxide of lead in nitric 

 acid, evaporated ihe solution to dryness, dissolved the salt 

 in water, and precipitated the protoxide by the addition of 

 the sulphate of ammonia. A little more sulphate of lead 

 was separated from the clear fluid by the addition of some 

 caustic ammonia, llie precipitate, collected and ignited, 

 weighed 20*36 gr. 



4.) The same quantity of the same protoxide treated with 

 nitric and sulphuric acid in a platina crucible, gave 20'363 

 gr. of sulphate of lead. 



According to these last experiments, 100 parts of sul- 

 phuric acid would saturate 279*59 of protoxide of lead. In 

 my future calculations, I shall take for the proportions of 

 sulphate of the protoxide of lead 



Sulphuric acid . . 26-385 100 35*8 



Protoxide of lead 73'6l5 279 100*0 



From all this it may be observed, how extremely difficult 

 it is to obtain a perfect coincidence in the results of analy- 

 tical experiments; a portion of the weight which is scarcely 

 if at all sensible on a loaded balance, has frequently a ma- 

 terial influence on the result of our calculations, in which 

 the error is often multiplied. 



D. Sulphuric Acid. 



I have shown by my earlier experiments that the sul- 

 phuret of lead and the sulphate of the protoxide contain 

 sulphur and lead in the same proportions. If now, accord- 

 ing to the first of these experiments on the sulphate (C), 

 and according to my former experiments, 100 parts of lead 



afford 



