Intelligence and Miscellaneous Articles. 153 



litmus paper; drying at 212°; weighing: — and lastly, igniting and 

 re -weighing. 



The medicinal solution above referred to (as to be diluted for ex- 

 periment in the proportion of one drop to the pint of water,) con- 

 tains, in round numbers, nearly a sixteenth of its own weight of an- 

 hydrous prussic acid, or rather less than four grains in the drachm, 

 being the article (commonly designated " of Scheele's strength,") as 

 manufactured by some respectable houses in London. We under- 

 stand that Messrs. William Allen and Co., by means of silver as a 

 reagent, have uniformly concentrated it to this degree since the 

 year 1820, when Mr. Barry introduced the use of that metal to de- 

 termine and regulate its proportion of absolute prussic acid by the 

 formation of cyanuret of silver. The method being one which ad- 

 mits of extreme precision, will deserve the attention of the College 

 of Physicians, if prussic acid be inserted in the next Pharmacopoeia. 

 It is to be recollected that tins preparation, like those of alcohol or 

 aether, is subject to variation, notwithstanding any superiority of 

 formula, or care on the part of the operator. Hence the necessity 

 of means for assaying the> final product and for reducing it to a uni- 

 form standard. With regard to the employment of cyanuret of po- 

 tassium for the occasional formation of hydrocyanic acid, it is a 

 question which at least deserves very serious consideration. Its dis- 

 position to absorb atmospheric moisture, and always to become more 

 or less converted into carbonate, while its cyanogen (united to hy- 

 drogen,) to an uncertain extent is dissipated, especially when this 

 beautiful salt is much disintegrated, constitute formidable difficulties. 

 But a still greater objection will present itself at the counters of 

 apothecaries and chemists where medicines are made up, from the 

 possibility of this intensely poisonous salt being sometimes mistaken 

 for other substances, in the frequent extemporaneous production of 

 prussic acid. 



OXALATE OF CHROME AND POTASH AND PROTOSULPHATE OF 

 IRON AND MAONESJA. 

 M. Gregori finds that double oxalate of chrome and potash, when 

 seen by reflected light, is black ; when placed between the eye and 

 the light it is blue, and when powdered it is green : when dissolved 

 in water, the solution in some points of view is green, and in others 

 red. He also finds that the double sulphate of magnesia and pro- 

 tosulphate of iron is of a bright green, and crystallizes in oblique 

 octahedrons. The composition of these salts has not yet been as- 

 certained. — Journal de Chimie Medicate, March 1833. 



NEW ACID IN NUX VOMICA. 



M. Coriol has discovered an acid in nux vomica which forms a 

 very soluble sidt with lime. It crystallizes in a granular mass in the 

 aqueous extract of nux vomica, treated with alcohol; the acid maybe 

 separated from the lime by oxalic acid. Me has also found another 

 acid in the nux vomica, which he is about to examine. — Ibid. 



Third Serin. Vol. i. No. 20. Feb. 1834. X 



