No. I.] 



GEOGNOSTICAL OBSERVATIONS. 



515 



ridge, rising two hundred feet above the spring. A small clayey plain on the 

 S.W. side of the eminence is traversed by the rivulet from the spring, and 

 opens into a bay of the river. A large and apparently-travelled fragment of 

 hornblendic gneiss lies on the acclivity under the spring, but the nearest 

 rocks observed in situ were composed of yellowish-white compact splintery 

 limestone. 



At the new Fort, a considerable distance above Pierre au Calumet, a lime- 

 stone similar to that last mentioned occurs, having its strata waved or dip- 

 Edinburgh, January 13, 1823. 



Dear Sir, 



Enclosed is an account of the experiments performed on the substances you sent me 

 for analysis. 



First incrustation of white matter from the lake near Carlton-House:— 



When put into water, it immediately agglutinated, forming minute hard globules which seemed to 

 prevent the farther action of the fluid ; but by heating it, it was entirely dissolved. The only sub- 

 stance I could detect in the solution by the use of re-agents was sulphuric acid in a state of com- 

 bination. I accordingly suspected that the white matter was effloresced sulphate of soda. To 

 ascertain if I was right in my suspicions, I dissolved a few grains by the aid of heat, and procured 

 from the solution a beautiful group of regularly-formed prismatic crystals, resembling those of sul-' 

 phate of soda, and which effloresced on exposure to a dry air. I consider the white matter then 

 to be merely sulphate of soda deprived of its water of crystallization by long exposure to the 

 atmosphere. 



Second deposition from the Salt Springs in the Elk River: — 



When recently broken, it presented in several places groups of irregular-shaped crystals, inter- 

 mixed with a white powdery matter, and with a yellow substance resembling flowers of sulphur. 

 It had a slightly saline taste, and, when rubbed, a faint sulphureous odour. When thrown on a hot 

 iron, it emitted blue flame and the vapour of sulphureous acid. By long boiling in successive 

 portions of water, it was almost all dissolved, the solution affording by the usual tests sulphuric acid, 

 muriatic acid, lime, and magnesia. The muriatic acid and magnesia were, however, in small 

 quantity compared to the others, and in the last portions of water in which the saline matter was boiled 

 could scarcely be detected. As it did not attract moisture on exposure to air, I suppose the 

 muriatic acid must have been in combination with soda, as muriates of lime and magnesia are both 

 deliquescent. What was left undissolved by the water contained sulphur and a very minute 

 quantity of iron. 



I consider this incrustation, then, as composed principally of sulphate of lime, with a slight 

 admixture of sulphate of magnesia and muriate of soda, and with sulphur and iron. 



I regret that the time allotted me for the analyses was not sufficient to enable me to ascertain the 

 proportion of the ingredients. Yours, &c. 



Andrew Fyfe. 

 3 U 2 



