Chemical Science, 4SSI 



boiling distilled water, left a flocculent olive coloured residue undis- 

 solved. This substance beinp^ separated, washed and dried, was 

 examined. Being heated on platina, it burnt into a vitreous sub- 

 stance. Another portion, heated in nitric acid, caused the evolution 

 of nitrous acid, and by evaporation gave a vitreous substance, which, 

 dissolved in water, produced a flocculent precipitate with baryta 

 water. The olive substance, in fact, was found to be boron, and 

 the product of its combustion boracic acid. — Bull. Univ. 



11. Preparation of Hydriodic Add. — Dissolve sixty grains of 

 iodine in a sufficient quantity of alcohol ; diffuse one ounce of finely 

 divided starch through four ounces of water, and add this, drop by 

 drop, to the former solution ; allow the iodide of starch to settle, 

 and pour off the clear liquid. Pass a current of sulphuretted 

 hydrogen through the deposit, the colour will at first change to 

 orange yellow from the formation of an iodide of sulphur, then it 

 will become yellow, and ultimately white. The whole is to be 

 filtered, the insoluble part washed with small quantities of water, 

 and the solution slightly heated to dissipate the sulphuretted 

 hydrogen. The solution may be obtained of specific gravity 1.5, 

 and is pure hydriodic acid. — Brande's Archives^ xxii. 45. 



12. Formation of Cyanide of Potassium. — When nitrogen gas 

 is passed over a mixture of potash and charcoal, heated to redness, 

 a considerable quantity of cyanide of potassium is obtained. When 

 ammoniacal gas is passed over a heated mixture of carbonate of 

 potash and charcoal, the same result is produced. — Ann. de Chimici 

 xxxviii. 158. 



13. Phosphoric Acid in Potash. — According to M. Kobell, phos- 

 phoric acid is found in nearly all potash, in crude tartar, and in the 

 ashes of most plants. It may usually be found in potash by 

 saturating the alkali with muriatic acid, evaporating and crystalliz- 

 ing, redissolving the crystals, adding ammonia to the solution, and 

 then muriate of lime. A precipitate forms more or less slowly, 

 which has the characters of phosphate of lime before the blow-pipe, 

 and moistened by sulphuric acid, communicates a green colour to 

 the flame of a spirit lamp. — Kastnefs Archives, viii. 323. 



14. New Compound of Silica andPotassa. — ^This compound, which 

 has been prepared and described by M. Fuchs, is intermediate 

 between glass and the oil of flints. It may be prepared by saturat- 

 ing a boiling solution of potash with recently precipitated silica; 

 but better by the following process. Fuse a mixture of ten parts 

 carbonate of potash, fifteen of quartz, and one of charcoal ; pulver- 

 ise the product, and dissolve it in four or five parts of boiling water, 

 which will slowly take up nearly the whole. The solution evapo- 

 rated until of a specific gravity of 1.24 will be a viscid, opalescent 

 liquid, which, whether evaporated further, quickly or spontaneously. 



