Berzelius o)i the Use of the Blow-pipe. 329 



tect the presence of muriatic acid. The application of the last 

 test is very ingenious. 



" We fuse oxide of copper with salt of phosphorus into a 

 dark-green globule, we then add the assay, and heat the whole 

 before the blow-pipe. If it contain muriatic acid, the globule is 

 surrounded by a fine blue flame, inclining to purple, which 

 continues as long as any muriatic acid remains in the assay. 

 Not one of the other mineral acids produces a similar pheno- 

 menon, and such of them as foni cupreous salts, which do of 

 themselves colour the blow-pipe flame, lose that property when 

 combined with salt of phosphorus. For instance, the earthy 

 mineral, in which the blue carbonate of copper (from Chessy, 

 in France) occurs, communicates an intense green colour to the 

 flame when heated before the blow-pipe ; but when treated with 

 salt of phosphorus, previously saturated with oxide of copper, 

 not the slightest colour is any longer perceptible in the flame." 



Under the head of General Rules for Experiments with the 

 Blow-pipe, much valuable information as to the size of the 

 assay, and the order to be observed in experimenting, is given, 

 which our limits will not allow us to detail. We recommend a 

 careful perusal of them to our readers. 



The next division treats of the phenomena presented by 

 diffierent mineral substances before the blow-pipe. The expe- 

 riments were made, as the author assures us in his introduc- 

 tion, on pure substances, and present a number of instructive 

 and valuable facts. The effects produced by the fluxes on 

 oxide of titanium, both pure and mixed with iron, and the 

 means of distinguishing it from the glasses of ferruginous 

 tungstic acid, ferruginous antimonious acid, and oxide of 

 nickel, which assume the same shade as ferruginous oxide of 

 titanium in the reducing flame, are very minute and important. 



Oxide of cadmium, " on charcoal is dissipated in a few 

 seconds, and the charcoal is covered with a red or orange- 

 yellow powder. This phenomenon is so marked with oxide of 

 cadmium, that minerals, which, like carbonate of zinc, contain 

 one or two per cent, of carbonate of cadmium, when exposed 

 for a single instant to the reducing flame, deposit, at a little 

 distance from the assay, a yellow or orange-coloured ring of the 

 oxide, most distinct when the charcoal is cold. This ring forms 

 long before the oxide of zinc begins to be reduced, and if 

 flocculi of that metal appear at the same time, it is a proof 

 that the blast has been pushed too far ; but if we can discover 

 no yellow trace before the fumes of zinc begin to condense on 

 the charcoal, we may conclude tliat the assay contains no 

 cadmium." 



Mr. Children has added the following in a note, on this sub- 

 ject, which he had from the late Dr. E. D. Clarke. " If platina 

 foil be used for the support, instead of charcoal, the yellow or 



