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Transactions 



Chemical Investigation. — On treating the powdered basalt 

 with dilute hydrochloric (HC1) or sulphuric (H 2 S0 4 ) acids, 

 gelatinization takes place in a most pronounced manner. A 

 pinch of about 0-5 gramme powder was placed in a test-tube 

 and covered with 0-5 in. of 50 per cent. HC1. It was brought 

 to the boiling-point and then allowed to cool ; by the time 

 it was cool it had formed a thick jelly, and test-tube could be 

 inverted at an angle of 45° from the vertical ; five minutes 

 later it could be held upside down without any movement 

 of the jelly taking place. To the hot solution obtained by 

 boiling the powder with HC1, H 2 S0 4 was added ; part was 

 allowed to stand for some days, when a quantity of gypsum 

 needles were thrown down ; part was at once evaporated to 

 dryness on a glass slide, and crystals of gypsum and halite 

 were then detected under the microscope. 



A sample of the powder was next boiled for five minutes 

 with dilute HC1, filtered and well washed ; the residue con- 

 tained colloid silica, which was dissolved by boiling for fifteen 

 minutes in strong KHO ; this residue was then filtered and 

 washed, and the filtrate evaporated to dryness. Each of the 

 three portions thus obtained was separately analysed, with the 

 following result : — 



The powder that was not dissolved by the HC1 was found 

 under the microscope to consist of augite and a little magne- 

 tite, so that the minerals which dissolved so readily were plagio- 

 clase, olivine, and magnetite. 



