Chemistry and Physics. 260 



rf determining the quantity of 



sen in 



Organic Substances; by Eug. Peligot, (Comptes Rendus, March, 

 1847.)— The method of Varrentrapp and Will was considered a great 

 improvement in the determination of nitrogen, particularly on account 

 of the saving of time, &c. But this process although requiring only a 

 short combustion, needs a prolonged manipulation of the platinum salt, 

 and is liable to several species of error. 



The method of Peligot is a simple alteration of that of Varrentrapp 

 and Will. The combustion is performed in the same manner, but the 

 ammonia is condensed by a known quantity (by volume or weight) of 

 sulphuric acid. After the combustion, this acid is transferred to a cyl- 

 indrical vessel, the washings added, and the strength of the acid deter- 

 mined by the volumetric method. The difference between this and 

 the original strength gives the quantity of acid saturated by the ammo- 

 ma, and consequently the ammonia. 



ror this last determination, the author prefers the solution of caustic 

 nme in syrup. This solution preserved in close vessels undergoes no 

 change, and even after absorbing carbonic acid from the air, it needs 

 °n'y a filtration to fit it for use. The strength of the alkaline solution 

 must be previously ascertained by the usual methods. 



A he results are accurate — an analysis of oxamide gave 31*3 per cent, 

 nitrogen, theory requiring 31*7. By this method a determination of 

 nitrogen may be made in less than half an hour, with an accuracy at 

 east equal to that obtained by the usual methods which require never 

 le ss than three hours. 



M. Peligot considers this method peculiarly useful in the case of 

 Physiological investigations, as the determinations, being useless unless 

 comparative and therefore numerous, may be multiplied almost without 

 trouble or expense. G. C. Schaeffer. 



5. Preparation of Sulphocyanid of Ammonium ; by J. Liebig, (Lie- 

 bl o s Annalen; Jan., 1847.) — A small quantity of sulphuret of ammo- 

 niUn ? l1[ i the presence of excess of sulphur produces the unlimited con- 

 Version of cyanid of ammonium into sulpho-cyanid — hence the following 

 process: 2 oz. sol. caustic ammonia, sp. gr. 0-95, are saturated into 

 sulphuretted hydrogen, and then mixed with 6 oz. of the same solution 

 01 ammonia ; 2 oz. flowers of sulphur are next added, and then the 

 Product of the distillation of 6 oz. prussiate of potash, 3 oz. sulphuric 

 j^d and 18 oz. water. The mixture is digested in the water bath until 

 ne sulphur is no longer acted upon and the liquid becomes yellow ; 

 1 ls then boiled till the sulphuret of ammonia is driven off and the liquid 

 , as . a gain become colorless. The excess of sulphur being removed, the 

 "quid yields on evaporation over 3 oz. pure white sulphocyanid, which 

 a y be used as a reagent instead of the sulphocyanid of potassium, 

 aff a reaction of prussic acid with the higher sulphurets of ammonium 

 salt a Ver y S ood test for the acid > as lhe sulphocyanides and per- 

 * lts of iron are more delicate tests for each other than the component 

 Jj^des and iron salts forming prussian and other blues. G.C. S. 

 , b - On the Decomposition of Nitrite of Ammonia; by E. Millon, 

 tta r de Chem " et de Ph y s -> Feb ' 5 1847 -)— Heat decomposes the solu- 

 bur? ite of amm <™ia, water being formed and nitrogen given off; 

 n a drop of caustic ammonia is added to some of the solution in a 



