380 Miscellaneous Intelligence. 



potash. The result was much inflammable gas, a pyrophorus 

 powder, and 180 grains of potassium. 



When iron alone was used, not a particle of potassium could 

 be obtained at the heat, to which only this apparatus could be 

 raised. 



Crude tartar was then used ; it was introduced into the appa- 

 ratus and heated, till the acid was decomposed ; then the tube 

 removed, cleaned, and again attached, and the heat raised as in 

 the ordinary process. The mean of many experiments gave 

 nearly 300 grains of potassium from 24 ounces of crude tartar. 

 Not more than an ounce of alkali was found at any one time in 

 the retort after the operation. When the tartar was previously 

 mixed with -^^ of charcoal, the product was greater. 



In the preparation of sodium, caustic soda, and the subcar- 

 bonate of soda were both used at different times, and with the 

 same success as attended the former experiments. 



M. Brunner remarks, that a large quantity of the metal con- 

 tained in the alkali, always disappeared in these experi- 

 ments ; and concludes, that it was carried off in vapour. He 

 endeavoured to condense it, but without success. He states, in 

 conclusion, that the apparatus is cheap and durable, having 

 served for as many as thirty operations : that the process is 

 easy and agreeable compared to that by iron at the high tem- 

 perature : and that, as the vegetable salts with a little additional 

 charcoal, are the best sources of the metals, so the process be- 

 comes very economical. — Bib. Univ. xxii. 36. 



7. Hydrocyanic acid, Preparation of.—M. Pessina, of Milan, 

 prepares hydrocyanic acid in the following manner, which is said 

 to be much more economical than any other process known. Eigh- 

 teen parts of triple prussiate of potash and iron are powdered 

 very fine, and carefully introduced into the bulb of a small 

 tubulated glass retort, a very small tubulated balloon is then 

 attached to the retort; it is furnished with a conducting tube 

 which dips into the first flask, containing a little distilled water. 

 The rest of the apparatus is contrived so as to prevent absorp- 

 tion. A cold mixture of nine parts of oil of vitriol, and twelve 

 parts of water, is then poured into the retort, the retort closed 

 and the whole left for 12 hours, the balloon being surrounded 

 with ice, and the neck of the retort constantly cooled with wet 

 cloths. — The materials are then to be heated a little, and con- 

 tinued so until the stria?, which are observed in the neck of 

 the retort become more rare, and, until a blue substance rises, 

 which appears as if it would pass into the receiver. The heat 

 is then to be discontinued, the apparatus allowed to cool, and 

 the contents of the receiver preserved in a proper vessel. The 

 hydrocyanic acid, thus obtained, is perfectly pure, and of a 

 specific gravity of 0.898 or 0.9. Its quantity, in relation to the 



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