94 Ber'zelius's Experiments to determine the Composition [Feb. 



quantity of oxygen which must exist in the base capable of satu- 

 rating 100 of the acid, is then 29-184, instead of 29*454 as I had 

 found it in my former experiments. It is equally evident that 

 these data are sufficient for calculating the composition of 

 muriatic acid, oxymuriatic acid, and oxymuriate of potash. But 

 I pass by these calculations in silence as they are foreign to the 

 object which 1 have in view. 



Oxide of Lead. 



It is of very great importance to know accurately the compo- 

 sition of the oxide of lead, especially in consequence of its great 

 influence in the analysis of organic bodies. Although in my 

 former and numerous experiments on this oxide, I obtained 

 results which agreed with each other, I thought it necessary to 

 repeat them, in order, if possible, to bring them to a greater 

 degree of precision. 



1 . Composition of Oxide of Lead found by direct Analysis. — 

 Among the analytical methods which depend the least upon the 

 dexterity of the operator, I conceive that the following occupies 

 the first rank. In a glass globe blown in the middle of a piece 

 of barometer tube, a quantity of oxide of lead was introduced 

 which had just been exposed to a red heat. The glass ball was 

 now heated by a spirit lamp, and a current of hydrogen gas pre- 

 pared from distilled zinc, and sulphuric or muriatic acid was 

 passed through it. The oxide becomes at first black, small 

 globules of reduced lead are seen, and after an interval of two 

 hours, it is converted into melted lead. The lamp is withdrawn, 

 and the lead is allowed to cool, while the hydrogen gas still con- 

 tinues to pass. If we weigh in the first place the tube of glass 

 alone, then when it contams the oxide of lead, and lastly when 

 it contains the reduced lead, the only possible error must proceed 

 from inaccuracy in weighing, provided we have employed a 

 hydrogen gas absolutely free IVom sulphur. 



I made m this way three experiments : 



(1.) 21*9425 grammes of oxide of lead left 20-3695 grammes 

 of metallic lead ; that is to say, that lOO lead had been united 

 with 7-7223 oxygen. 



(2.) lU-8646 gr. of oxide of lead yielded 10-084 gr. of lead. 

 Equivalent to 1 00 lead united to 7-74 oxygen. 



(3.) 11-169 gr. of oxide of lead yielded 10-359 gr. of lead. 

 Equivalent to 100 lead united to 7-7228 oxygen. 



2. Composition of Oiide of Lead determined by a Calculation 

 ivhicli /lasjur its Basis the Analysis of titrate oj Lead.— From 

 an analytical experiment on nitrate of lead, 100 of the nitrate 

 yield ()7-31 of oxide of lead; but we know that nitric acid is 

 composed of 1 volume of azotic gas and 2J- volumes of oxygen 

 gas, and that (neglecting the oxygen piKibably contained in the 

 azote) this acid contains five times as much oxygen as the base 

 by which it is neutralized. If we determine the composition of 



