64 



Several analyses have been made, taking fragments from different 

 localities, and a close agreement was found In the results ; proving an 

 equality of composition quite unusual In uncrystalllzed compound 

 minerals. 



In these analyses, the boric acid was weighed In combination with 

 magnesia, by the following method : — 



1. A trial gave the proportion of bases present. 



2. 25 grains of very fine powder of the mineral were dropped Into 

 a flask containing 500 grains of pure water, boiling hot : 30 grains of 

 crystals of pure oxalic acid were added, and the boiling continued 

 until the oxalates would rapidly fall to the bottom of the flask, as a 

 heavy granular powder. 



The clear solution contained nearly all the silicic and boric acids. 

 Without removing it from the flask, it was cooled and agitated while 

 a slight excess of pure ammonia was added ; the whole again warmed 

 and finally cooled, when the silica, combined with lime and mixed 

 with oxalate of lime, was a granular powder which could be easily 

 and accurately washed. A trace of copper oxide and the whole 

 boric acid, with some excess of oxalic acid and ammonia, were In the 

 filtrate ; sulphydric acid removed copper, and the filtrate mixed with 

 a weighed quantity of recently calcined and cool magnesia, the water 

 evaporated by steam bath, and the residue calcined, the Increase of 

 weight In the magnesia was pure boric acid. The other constituents 

 were determined as usual, using the oxalates. 



It will be seen that this mineral Is less hydrous than crystallized 

 Dathollte. The fine powder of the masses loses at 300° F. 0.36 per 

 cent, moisture. Slowly heated to redness the loss Increases to about 

 3.96 per cent., but a sudden elevation of temperature causes a loss of 

 acid, apparently due to the action of silicic acid of the silicates in 

 expelling It. A slight loss of acid in this way has occurred in these 

 experiments, and a closer determination would show the existence of 

 little less water. It Is possible, too, that the water in crystallized 

 Dathollte has been overrated In consequence of an error arising from 

 the volatility of hydrous boric acid in presence of silica. 



Apart from any scientific interest belonging to this mineral, It has 

 important economical relations. It may be used in the manufacture 

 of borax, as It contains nearly one half as much pure boric acid as 

 is found in commercial boric acid. 



Some experiments made by my friend, Dr. Keep, and repeated by 

 myself, prove that It may replace borax in many most important ap- 

 plications, without any chemical change previously ; the careful selec- 

 tion of fragments only being required. 



