Analysis of the Pittsburgh Mineral Sprhig. 129 



ebrated chalybeates in Europe, and even in this country, 

 none of them are stated to contain more, and few of them 

 so much. It is even probable that if this water were ex- 

 amined when immediately taken from the spring, it would 

 be found to contain more of this gas. 



SECTION IV. 



Examination of the contents of the Pittsburgh Mineral 

 Spring by Evaporation. 



The experiments which have already been detailed throw 

 great light on the qualities of this water, and enable the ex- 

 perienced chemist to decide upon the nature, but not on the 

 quantity of the different substances with which it is impreg- 

 nated. To make an accurate estimate of these I proceeded 

 to evaporate one quart of water in a glazed China vessel, 

 placed in a sand bath over a furnace. Heat was gradually 

 applied, but never allowed to exceed 180 or 200 of Fahren- 

 heit, when the gas began to arise, the water became slightly 

 turbid, and a light pellicle appeared on its surface, which 

 gradually subsided to the bottom of the vessel ; and when 

 the water was evaporated to dryness, the whole of the resi- 

 duum or solid contents which was collected, amounted to 4 

 grains. This powder when exposed to the atmosphere for 

 several days, showed no signs of deliquescence, nor was it 

 sensibly increased in weight. In order to determine the 

 component parts of these four grains, I proceeded in the fol- 

 lowing manner. I poured over it, in a small phial bottle, 

 about half an ounce of alcohol of the specific gravity .827 

 and shook it repeatedly for twenty four hours ; then filtered 

 it carefully, when I found that it had lost in weight only half 

 a grain, which was the whole that the alcohol had taken up. 

 The residue now reduced to three and a half grains, was 

 treated with an ounce of pure distilled water, and having 

 left it sufficiently long to complete the solution of whatever 

 was soluble in pure water, I again filtered it carefully, and 

 dried the residuum which was now reduced to one and a 

 half grains. 



Only this residuum which resisted the action of alcohol 

 and of distilled water, remained to be examined, and, as 

 from former experiments I had satisfied myself that it must 

 consist principally of the iron and earths contained in the 

 water, I re-dissolved it in dilute marine acid which took up 



Vol. XIV.— No. 1. 17 



