Atomic Volume and Specific Gramty. 313 



peth mineral. On throwing 57*4 grains of this salt thus pre- 

 pared into water, an increase of 6*9 was obtained, which gives 

 44*3 as the volume of the equivalent, and 8*319 as the spe- 

 jfjific gravity of the salt. /.rui;;' i 



-^.y.Chromate of Lead, PbO, CrOg = 1 G3 '9 7. -Tfdjj^ii^^jWfpg 

 81*98 grains of the chromate of lead, previously well-dried, 

 into turpentine, an increase of 14*5 was effected; this gives 

 ,;^9'0 as the volume of the equivalent, and 5*653 as the speci^c 

 gravity of the salt. , , ■ 



S],Subchromate of Lead, VhO,QvO,^ + PbO = 275-7.— this 

 salt was prepared by projecting chromate of lead into melted 

 nitre, and afterwards washing out all soluble matter. On im- 

 jipersing 68*92 grains, the fourth part of an equivalent, an in- 

 crease of iro was obtained in two experiments. This gives 

 44*0 for the volume of the equivalent, and 6*266 as the spe- 

 cific gravity of the salt. 



Sesquibasic Chromate of Lead, 2 (PbO, CrOg) + PbO = 

 439*67. — The mineral, melanchroit, is of the composition ex- 

 pressed by the above formula, and has a specific gravity of 

 5*75 according to Hermann ; this gives the number 7^6*5 as the 

 atomic volume of the compound. 



^^'\ Subnifrale of Copper, CuO, NO5, HO, 2CuO = 182-l7M- 

 "^e fourth part of an equivalent, 45*54 grains, caused an ia-; 

 'crease of 16*5 in two experiments, and of 16*4 in a third. '^* 



i:;! 1 ii.'vi II 



— -^ifivAGm ni sotsb v[jobx9 B;tn3fr! Sp. gr. 



I. G!u0>NO5,HO -h2CuO, voLofsalt 66-0 ... 2*760 



II. I- . i i: ... ■■■;• 1W lu ,lo7 ..-Wx b. 66*0 ...2*760 



WMes=:^(r^6,0.sH,^^m\^ - ^.^ •" ^'^^^ 

 i ::r, ^fT'^.r.r/r »>.>-,. 'r> ,-rrf%rr,„ ?r.,, . Mean . . 65*87 ••• 2*765 



A'. Suhnitrate of Bismuth, BiO, NO5, HO + 2BiO = 300*4. 

 — This salt was prepared in the same manner as subnitrate of 

 copper, viz. by heating the nitrate to 400° or 500°. The fourth 

 part of an equivalent, 75*1 grains, thrown into water, caused^ 

 in various experiments, an increase of 16*5, which gives 66*0 

 as the atomic volume, and 4*551 as the specific gravity of the 

 salt. V 1 



B. Subnitrate of Bismuth, BiO, NO5 + 2BiO = 291'4..*^ 

 This salt was prepared by adding nitrate of bismuth to a 

 large quantity of water ; the white powder which falls by this 

 treatment, is composed, according to Phillips, of three equiva- 

 lents of oxide of bismuth united to one of nitric acid. It is 

 therefore the same salt as the one last described, deprived of 

 its constitutional water. On immersing 72*85 grains of the 

 salt in water, a rise in the stem of 13*9 was eifected, and 36'4u? 

 grains treated in the same way gave an increase of G'^wog^ ;9i : 



