6 THE ROYAL SOCIETY OF CANADA 



PVROG NOS TICS, ETC. 



Before the blowpipe the mineral, though mixed with some 

 chrysotile serpentine and dolomite fuses readily with little or no 

 intumescence or exfoliation, imparting a green colour to the fîame. 

 The fused material is brownish black and opaque. It is soluble In 

 HCl, H2SO4 and HNO3. The hardness Is less than 3. It is readily 

 distinguishable from sussexite by the smaller manganese content. 



Preparation of Thin Sections 



Owing to the softness of the borate and the crumbly character 

 of the whole mixture it was quite impossible to prepare sections in 

 the ordinary way. An account of the procedure by which excellent 

 sections were prepared, therefore, may be of Interest. 



The masses of borate mixture were sawn Into pieces about two 

 inches square, which were Immersed in a not too concentrated solution 

 of Canada Balsam in benzol. The Canada Balsam previous to 

 solution in benzol had been heated to drive off the more volatile 

 constituents until on cooling It had the correct degree of hardness for 

 grinding. The beaker containing the squares Immersed In the solution 

 was then placed in a strong glass vessel and subjected to vacuum. 

 There was for two or three hours abundant evolution of air from the 

 squares, and when this finally ceased, normal atmospheric pressure 

 was restored. The solution was then allowed I0 evaporate over- 

 night until it had reached a syrupy consistency, when the squares 

 were removed and placed In an electric oven at 50^C. After about 

 24 hours the squares were dry and could be worked In the usual way 

 by sawing and grinding. 



The heating In the oven, an undesirable feature which was 

 adopted merely to save time, caused oxidation of the iron and man- 

 ganese of the borate, which became darker in colour, no doubt accentu- 

 ating the^bsorption observed In sections in polarized light. 



It Is. likely that an ether solution of balsam would be better than 

 the benzol solution for the preliminary soaking process owing to its 

 lower boiling point. 



Optical Properties 



The sample prepared for analysis when examined under the 

 microscope was seen to consist chiefly of minute fibres of camselllte 

 showing parallel extinction and high birefringence. There were 

 minor amounts of dolomite and chrysotile present, the formel readily 



