172 Miscellaneous Intelligence. 



two conductors by another arch of the same kind ; these, therefore, 

 act as the positive and negative conductors. There is no undue 

 strain upon any part of this machine, and it is found on practice to 

 excite well and insulate perfectly. — F/iiL Mag. lxii. 8. 



24. Carbonic and Muriatic Acids of the Atmosphere. — According 

 to M. Vogel, scarcely any carbonic acid can be found in the atmo- 

 sphere over the sea two or three miles from shore, even barytes water 

 almost fails to detect it. On the other hand, various Dutch chemists 

 have pointed out the existence of muriates, and even free muriatic 

 acid in the atmosphere. The latter seems most decided near the 

 sea-shore, and is most abundant in dry weather. At Amsterdam it 

 appeared to be particularly abundant; but is attributed in part, at 

 least, to the action of sulphuric acid formed by the combustion of coal 

 and peat, which acting on the muriates set their acid free. 



25. Vegetable Alkali from Rhubarb. — M. Nani, of Milan, states, 

 that he has discovered a new vegetable alkali in rhubarb j but has 

 not, as yet, said much of its properties, and except its solubility in 

 weak sulphuric acid, and precipitation by lime, no evidence of its 

 alkaline nature is offered. Six ounces of rhubarb in powder were 

 boiled for two hours in eight pints of common water with four drams 

 of sulphuric acid, it was filtered, pressed, and the residuum re-boiled 

 with six ounces of water and two drams of sulphuric acid, the fluid 

 being again separated, the residuum weighed but two ounces. The 

 united infusions were mixed by degrees with three ounces of quick- 

 lime, and from being yellow became of a blood-red colour ; after 

 standing a day the precipitate was filtered out, dried in the sun, and 

 weighed six ounces. It was then digested at a high heat with four 

 pounds of alcohol of specific gravity .837 for two hours, filtered, 

 and again digested with two pounds more of alcohol, which, when 

 separated by a second filtration, was added to the first. Being put 

 into a retort, five pounds of the alcohol were distilled ofT, and the rest 

 of the liquor evaporated carefully to dryness. It weighed two drams, 

 was qf a red-brown colour, with brilliant points throughout it. Its 

 taste was sharp and styptic. It was soluble in water, and its odour 

 was like that of rhubarb. 



This preparation is recommended in pharmacy as being of constant 

 quality, of convenient solubility in water, and deprived of its inert and 

 ligneous matter ; one or two grains is sufficient for a dose. — Bib. Uni. 

 xxii. 232. 



26. Change of Fat in Perkins's Engine, by Water, Heat .fid 

 Pressure. — Mr. Perkins uses in his steam cylinder a mixture of 

 about equal parts of Russia tallow and olive oil to lubricate the 

 piston and diminish friction. This mixture is consequently exposed 

 to the action of steam at considerable pressure and temperature, and 

 being carried on by the steam, it is found in the water giving rise to 

 peculiar appearances. 





