1 j:§3.] Scientific Intelligehc^'^^ 69 



a light amber colour, and deposited crystals of an orange-yellow colour,, 

 the quantity of which increased for some time. The solution in which 

 they were formed was examined ; it had a strong smell of hydrocyanic 

 acid, and was alkaline; it gave a bluish-green precipitate with sulphate 

 of iron, which a drop of sulphuric acid immediately rendered blue. 

 From these effects, M. Vauquelin concludes, that thesolutioii of cya- 

 nogen was converted into hydrocyanate of ammonia. 



The crystals obtained were dendritical, and had no particular snlell 

 or taste; they were nearly insoluble in water; solution of potash did 

 not disengage any thing ; it did not dissolve them; nor did the mixture 

 give any l)lue precipitate with sulphate of iron. When heated in a 

 tube into which a piece of paper was introduced moistened with sul- 

 phate of iron, the paper became blue, and there was a strong smell of 

 hydrocyanate of ammonia. M. Vauquelin thinks it probable, that in 

 this case, the carbon which is usually deposited from cyanogen during 

 decomposition, had combined with a portion of the undecompbsed 

 cyanogen, and thus become insoluble, and precipitating slowly, it 

 had time to combine with a small quantity of water, and assume the 

 crystalline form. M. Vauquelin proposes to call this substance suh^ 

 cyanogen or protocijanogen* — ( Annales de Ghimie et de Physique.) 



VI. Preparation of Iodide of Potassium, 



M. Caillot suggests the following method of preparing this com- 

 pound: — Hydriodate of iron is first formed, and then decomposed by 

 carbonate of potash ; for this purpose he takes four parts of iodine, 

 two of bright iron filings, and about twenty of water. These three 

 substances are to be put in a glass or porcelain capsule. The mixture 

 is to be stirred until the liquor which soon becomes of a deep-brown 

 colour, is rendered colourless ; the liquor is then made to boil, and a 

 solution of subcarbonate of potash is to be added until precipitation 

 ceases ; or a small excess of the alkali may be used, and saturated with 

 hydriodic acid after filtration. The residuum is to be washed till it 

 ceases to afford a precipitate on the addition of permuriate of mercury: 

 the filtered liquors being then mixed, the whole is to he evaporated till 

 a pellicle appears. 



The same process may be employed for. preparing the iodides of so- 

 dium, magnesium, calcium, &c. The iodides of mercury may also be 

 prepared by decomposing the protonitrate and permuriate of mercury 

 by means of hydriodate of iron, which, as just shown, may be formed 

 extemporaneously. — (Annales de Ghimie et de Physique.) 



Vir. Butter. 



M. Chevreul has lately subjected the butter of cows' milk to exami- 

 nation. He finds that 100 parts of fresh butter consist of 



Pure butter 8375 



Butter-milk 16-25 



From numerous experiments, M. Chevreul concludes that there exist 

 in the oil of butter at least two fluid substances, onei of which is soluble 

 in all proportions in cold alcohol, does not possess acid properties, and 

 gives by saponification some sweet principle, butiric, caproic, capric^i 



