116 



Mr. E. Schniack on the Colouring and 



[RecesSj 



water, and to the solution acetate of lead was added, wliicli gave a slight 

 precipitate. The filtered liquid was mixed with a large quantity of alcohol, 

 which produced a cream-coloured precipitate. This was filtered off and 

 prepared in the usual manner for analysis. 



IV. 1'0485 grm. gave 0*6810 grm. carbonic acid and 0*2195 grm. water. 



1*5440 grm. gave 0*2755 grm. chloride of platinum and ammonium. 



0*6120 grm. gave 0*4820 grm. sulphate of lead. 



In 100 parts it contained therefore 



C 17*71 



H 2*32 



N 1*12 



O . 20*90 



PbO 57-95 



100-00 



The substance combined with oxide of lead contained, in 100 parts, 



C 42*11 



II 5-51 



N 2-66 



O 49*72 



100*00 



It will be seen that this analysis yielded numbers not differing very widely 

 from those of Analysis II. Series D. The composition of the extractive 

 matter combined with oxide of lead corresponds in both cases with the for- 

 mula Cg^ NOg^. A comparison of the tv/o analyses affords also a 

 further corroboration of Avhat has been stated above, viz. that in the lead 

 compounds containing chloride of lead, the latter replaces the same weight, 

 not an equivalent quantity of oxide of lead. The difference between the 

 amount of oxide of lead of the one compound and that of the chloride and 

 oxide taken together of the other, is in this case greater than in those before 

 referred to. 



The precipitate produced by ammonia in the liquid filtered from that 

 with basic acetate of lead still remained to be examined. In consequence, 

 however, of a change of residence and other unforeseen circumstances the 

 investigation suffered a lengthened interruption at this stage, and was only 

 recommenced after an interval of two years. During this time the precipi- 

 tate was kept in well-stoppered bottles covered with water, so as to preserve 

 it moist and out of immediate contact with the atmosphere. It had under- 

 gone no perceptible change. It was therefore filtered off and treated with 

 dilute sulphuric acid. The excess of acid was removed by means of car- 

 bonate of lead, and the filtered liquid was evaporated at a moderate tempe- 

 rature in a hot-air stove instead of, as hitherto, by means of a current of 

 air, which I now no longer had the means of producing of the requisite 

 strength. The residue left after evaporation was treated with cold water, 

 which left a quantity of chloride of lead of a dirty-yellow colour undis- 



