Prof. E. J. Chapman on some Blowpipe Reactions. 461 



zinc oxide. When, therefore, the presence of cadmium is 

 suspected in the assay-substance, it is advisable to employ 

 the following process for its detection. The substance, if in 

 the metallic state, must first be gently roasted on a support of 

 porcelain or other non-reducing body. Some of the resulting 

 powder is then fused with borax or phosphor-salt on a loop of 

 platinum wire, and bisulphate of potash in several successive 

 portions is added to the fused bead. The latter is then shaken 

 off the wire into a small porcelain capsule, and treated with 

 boiling water. A bead of alkaline sulphide is next prepared 

 by fusing some bisulphate of potash on charcoal in a reducing 

 flame, and removing the fused mass before it hardens. A 

 portion of the solution in the capsule being tested with this, 

 a yellow precipitate will be produced if cadmium be present. 

 The precipitate can be collected by decantation or filtration, and 

 tested with some carbonate of soda on charcoal. This latter 

 operation is necessary, because if either antimony or arsenic 

 were present, an orange or yellow precipitate would also be 

 produced by the alkaline sulphide. By treatment with car- 

 bonate of soda on charcoal, however, the true nature of the 

 precipitate would be at once made known. 



On the Solubility of Bismuth Oxide in Carbonate of Soda 

 before the Blowpipe. — Neither in the treatise of Berzelius, nor 

 in the more modern and advanced work of Plattner, is any 

 reference made to the behaviour of oxide of bismuth with car- 

 bonate of soda in an oxidating flame. In Plattner's Tabel- 

 larische Uebersicht des Verhaltens der Alkalien, Erden, unci 

 Metalloxyde fur sich und mit Reagentien im Lothrohrfeuer, 

 whilst oxide of lead is stated, correctly, to be soluble in carbo- 

 nate of soda in an oxidating flame, the reference to oxide of 

 bismuth is simply, that with carbonate of soda on charcoal it 

 becomes immediately reduced to metallic bismuth ; and none 

 of his translators seem to have thought it necessary to supply 

 the omission. In Hartmann's tabular Untersuchungen mit dem 

 Lothrohr, in the handy little work of Bruno Kerl (Leitfaden 

 bei qualitative?! und quantitativen Lothrohr- Untersuchungen), 

 in the Lothrolir-TabeUen of Hirschwald, and all other blowpipe 

 books that I have met with, the same singular omission occurs. 

 This seems to bear out very forcibly the somewhat cynical 

 adage that " books are made from books." To supply the 

 omission, it may be observed that bismuth oxide dissolves in 

 carbonate of soda very readily in an oxidating flame, if the 

 supporting agent be platinum wire or other non-reducing body. 

 The glass is clear yellow whilst hot, but on cooling it assumes 

 an orange or yellowish-brown colour, and becomes pale-yellow 

 and opaque when cold. As regards their solubility by fusion 



