94 Geological Notices. 
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 ina 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 in forming ‘Cho 
_ 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 1 
make more detailed communications hereafter. 
a 
Art. XII.—Geological Notices; by Lieut. W. W. MatHer, of 
the Military Academy at West Point. 
1. Illustrations* of a Section through a part of Connecticut, fr = 
Killingly to Haddam on Connecticut River. (See the Sectio 
annexed.) 
Tue granular feldspar rock, of the accompanying section, was ae 
‘seen in place at Tyler’s and Bolles’ quarries, several miles north ° 
the section ; but it crosses the section about one and a half miles wes 
ok acinar 
' * From a paper communicated to the American Geological Society, by Lt M 
er, with a collection of specimens. ' 
