by Weight and by Volume. 21 1 



natant liquid is entirely removed ; by this means we may get the 

 requisite data for correction. 



The following experiments may serve as a critical illustration 

 of the various methods described above : — 



A. 5*640 grains of pure bismuth were dissolved in pure nitric 

 acid, and the solution evaporated to a syrupy consistence; by 

 evaporating in this way all excess of acid was expelled. So 

 much limpid water was then added as to increase the volume to 

 2820 grs. The liquid was divided into two equal portions ; one 

 solution precipitated with bichromate of potash in excess, and 

 the other with a mixture of caustic ammonia and carbonate of 

 ammonia. In the latter case the mixture was allowed to stand 

 at about 150° "F. for eight hours. They contained respectively 

 2*820 grs. of metallic bismuth. 



Amoimt indicated by the chromate"! „ mr./. 



of bismuth obtained . . . 1 3*8196 grs. 

 Amount indicated by the oxide ofH o oior. 



bismuth obtained .... j^2*8182 grs. 



Actual amount present .... 2*8200 grs. of bismuth. 



B. From 1000 grains of a solution of nitrate of bismuth of 

 unknown strength, the bismuth was precipitated by the insertion 

 of a plate of zinc, and the metal calculated from the roasted 

 oxide of bismuth. From precisely the same volume the bismuth 

 was precipitated in combination with chromic acid by means of 

 bichromate of potash. The amount of metal calculated from the 

 use of — 



Bichromate of potash = 2*174 grs. 

 Metallic zinc . . . = 2*112 grs. 



Difference . . . *062 gr. of bismuth. 



C. A solution of nitrate of bismuth containing exactly 3*639 

 grs. of bismuth was mixed with 3*205 grs. of copper as sulphate, 

 1*240 gr. of manganese also as sulphate, and several grains each 

 of nitrate of uranium, sulphate of zinc, and sulphate of iron. 



Found from the chromate of bismuth 3*6386 grs. 

 Amount actually present .... 3*6390 grs. 



DiiiVrence *0004 gr. of bismuth. 



D. To a solution containing 4*827 grains of bismuth, 5*100 

 grains of lead, and 3*724 grains of baryta, an excess of dilute 

 sulphuric acid was added, the temperature slightly elevated, and 

 the mixture filtered. After dissolving out the sulphate of bis- 

 muth with water slightly acidified with acetic acid, the filtrate 

 was evaporated until fumes of sulphuric acid began to be emitted ; 

 the fluid was then diluted with water, and supersaturated with a 



