THE CHEMICAL PROPERTIES and RELATIONS OF COLEMANITE. 



BY J. T. EVANS. 



At a regular meeting of the Academy held February 4, 1884, I 

 read a short paper giving simply the results of my analysis of 

 this new borate — its chemical formula — the angular inclination 

 of the vertical to the clinodiagonal and measurements of some of 

 the other more commonly occurring angles. All the determin- 

 ations embodied under the head " Colemanite," including both 

 the physical and chemical characteristics were made and verified 

 by myself. 



I have subsequently made repeated analyses of carefully 

 selected aud beautifully clear crystals of the mineral, and the 

 results confirm the correctness of my previously published analy- 

 ses and of the formula deduced. 



In the present paper I wish to specify in outline only some of 

 the experiments made and methods used in the chemical examin- 

 ation, leaving the further elaboration of the physical character- 

 istics in the able hands of Mr. Jackson, whose hearty co-oper- 

 ation I wish here to fully acknowledge. 



Preliminary to the following experiments, some of the purest 

 crystals obtainable were crushed to a very fine powder by 

 means of an agate mortar and pestle. 



A portion of the powder heated in a closed glass tube decrepi- 

 tates and passes into a very fine dust with simultaneous conden- 

 sation of a liquid in the cooler portions of the tube. The re- 

 action of this liquid is neutral; in a word, it is water. 



Heated alone before the blowpipe in a loop of platinum wire 

 or on charcoal, it fuses to a clear transparent glass which is milk 

 white on cooling. 



Heated on platinum wire with muriatic or sulphuric acid, it 

 gives a yellowish green flame of short duration — a yellowish red 

 more persistent and a transient soda-yellow flame. 



The powdered mineral dissolves readily and completely in 

 dilute muriatic or dilute nitric acid with the aid of a gentle 



