1821.] Scientific Intelligence. 155 



complete, the ashes containing less charcoal than the preceding. They 

 weighed only 112 lb. and produced 28 lb. of impure potash. 



Taking a mean result from the experiments made in Ireland and 

 Scotland, or even admitting the former to afford a better standard, 

 there is evidently no temptation, says Dr. Macculloch, for agricultu- 

 rists to repeat these trials with a view to profit ; for, on analysis, the 

 aline mass called impure potash did not contain above 10 per cent, of 

 pure alkali. — (Journal of Science.) 



III. Chromic and Sulphuric Acids. 



When sulphuric acid is boiled on chromate of lead or barytes in 

 excess, the chromic acid obtained is not pure, but contains sulphuric 

 acid. The liquid containing the two acids, when successively evapo- 

 rated, entirely crystallizes in small quadrangular prisms of a deep red 

 colour. If the heat and concentration be carried too far, oxygen is 

 disengaged, and sulphate of green oxide of chromium found. These 

 crystals are deliquescent, and contain one atom of each of the acids. 

 To analyze them, they were boiled with a mixture of muriatic acid 

 and alcohol, so as to convert the chromic acid into green oxide ; then, 

 dividing the liquid into two parts, one was precipitated by muriate of 

 barytes, to give the sulphuric acid ; and the other by ammonia, for the 

 oxide of chrome, and, consequently, the chromic acid. 



Alcohol easily dissolves this substance, and, if strong, so rapid a 

 decomposition is produced, as to resemble an explosion. The chromic 

 acid becomes oxide of chromium, and a particular ethereal odour is 

 produced. Having ascertained that the same odour was produced by 

 treating peroxide of manganese with alcohol and sulphuric acid, I col- 

 lected some of this ethereal fluid by distillation, and rectified it on lime 

 to separate water, and on chloride of calcium to separate alcohol. It 

 was then of an acrid burning taste, and very penetrating odour, resem- 

 bling sulphuric ether. When mixed with water, it separated into a 

 stratum of sulphuric ether, and a white transparent light oil, identical 

 with the sweet oil of wine. The mixture of alcohol, sulphuric acid, 

 and black oxide of manganese, that had been used, contained much 

 sulphate of manganese, but no hyposulphuric acid. 



Hence, in treating alcohol by chromic and sulphuric acid, or by the 

 latter and peroxide of manganese, it appears to undergo the same alte- 

 ration as by sulphuric acid alone. Sulphuric ether and sweet oil of 

 wine are formed by means of the oxygen of the chromic acid, or of 

 the peroxide of manganese. The sulphuric acid suffers no alteration, 

 but its presence is necessary to determine the decomposition of the 

 alcohol and the partial deoxidation of the chromic acid, or peroxide, 

 in consequence of its affinity for the oxides of chromium and man- 

 ganese. I do not doubt but that it might be replaced by many other 

 acids. 



M. Gay-Lussac, to whom these experiments are due, then observes, 

 that Scheele and Dobereiner had noticed effects relative to this sub- 

 ject. Scheele remarked the ethereal smell, &c. produced by the 

 action of peroxide of manganese, sulphuric acid, and alcohol, and 

 distilling slowly; and Dobereiner had observed a similar odour in a 



mixture of chromate of potash, sulphuric acid, and alcohol. — (Ann. 



de Grim. vol. xvi. p. 103.) 



