94 Geological JVotices. 



ing those scintillations, observable in the flame when common oil of 

 turpentine is used. These two peculiarities give fine tests of the 

 purity of the article ; but an infallible test of absolute purity is fur- 

 nished by dilute sulphuric acid, (equal weights of acid and water.) 

 Should there remain any impurity in the oil of turpentine, by agita- 

 ting the oil with acid, the resin will be charred, and thus discolor the 

 acid. If the sample be pure, no discoloration should follow, although 

 the oil should remain on the acid for some time. Generally oil of 

 turpentine purified by distillation, from water, on being agitated with 

 dilute sulphuric acid, give to the acid in a short time a beautiful claret 

 colored tint. 



The spirits of turpentine, forwarded by Mr. Guthrie, answers cor- 

 rectly to his description and must be valuable in several arts. Prob- 

 ably it would be useful in removing oil paints from clothes ; the com- 

 mon spirits of turpentine often leave a stain, owing to the resin which 

 they hold in solution. 



Preference of Caustic Potassa over the Carbonate informing Chlo- 

 rate of Potassa. 



In making chlorate of potassa, says Mr. Guthrie, I estimate the 

 product by the quantity of sulphuric acid necessary to obtain one 

 pound of crystals. With ten pounds of acid, I obtain, with caustic 

 potassa, one pound of crystals ; by using carbonate of potassa, I 

 should require seventeen pounds of acid to produce the same quantity. 



The above notices, as matters of fact, will probable be interesting 

 to the chemical public of this country. Mr. Guthrie promises to 

 make more detailed communications hereafter. 



Art. XII. — Geological JVotices; by Lieut. W. W. Mather, of 



the Military Academy at West Point. 



1. Illustrations* of a Section through a part of Connecticut, from 

 Killingly to Haddam on Connecticut River. (See the Section 

 annexed.) 



The granular feldspar rock, of the accompanying section, was first 

 seen in place at Tyler's and BoUes' quarries, several miles north of 

 the section ; but it crosses the section about one and a half miles west 



* From a paper communicated to the American Geological Society, by Lt. Math- 

 er, with a collection of specimens. 



