OF ARTS AND SCIE.NXES. 299 



ordinary salts, soluble silicates, not altered by boiling, drying, or heat 

 of 100° C. These waters attack crystal glass, leaving an incrustation, 

 which resists weak acids ; and they seem to be free to act in re-con- 

 solidating strata. Indeed, in the deep parts of the gravel deposits, we 

 meet with masses of rock in which solution of the silicates in water is 

 hourly going on ; and we may follow tliese solutions to the wells, and 

 observe that sometimes depositions are formed on the surfaces of the 

 rocks, over which they pass. 



Vanadium exists in the water, which supplies the wells of the dis- 

 trict of the drift, as a transparent, colorless solution of magnesian 

 calcic, manganous, and ferrous silioatea, phosphates, carbonates, and 

 vanadates. 



The deposit which fonns in the boiling water resembles in composi- 

 tion the matter as taken from rocks by weak solvents, although some 

 of these compounds remain dissolved in the water after it has been 

 boiled. 



Detection of vanadium as oxide is easily and at once effected, by 

 dissolving the deposit formed from boiling water, by means of diluted 

 nitric or sulphuric hydrate. In this solution, the addition of a slight 

 excess of ammonic hydrate, and a moment after a considerable excess 

 of ammonic carbonate, insures the reduction of any vanadic compouiul, 

 by the manganous and ferrous oxides, and separation of other com- 

 pounds than magnesic oxide and the blue vanadous oxide, which ap- 

 pears in solution of a rich blue color. In a nearly closed vessel, a 

 bright stiip of zinc will withdraw vanadous oxide from the blue solu- 

 tion, at first as a thin bronze coating, then after a black crust. 



I believe this is the first discovery of vanadic compounds in water. 

 Before announcing it, every source of error has been scanned ; and the 

 labor of connecting the compounds with the rocks where they originate 

 has been performed, as necessary to completeness, in the evidence. 



Manganous salts have been observed in waters where humic acid 

 has acted on rocks containing manganous carbonate, and the existence 

 of a water of this kind is known to me ; but it must be considered quite 

 apart in composition from a water in which soluble silicates include 

 manganous silicate as part of a compound possessing novel characters. 



In concluding this brief account of results proving the existence of 

 phosphates and vanadic compounds in the cementing material of the 

 most common rocks, I wish it to be considered as only introductory to 

 a wide field of interesting research. 



