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VII, — On the Emjployment of Dammar in Microscopy. 



By Prof. Abthur Mead Edwards, New York. 



In the London 'Quarterly Journal of Microscopical Science' for 

 January, 1871, appeared an extremely interesting and valuable 

 paper by Mr. Henry N. Moseley, " On the Use of Nitrate of Silver 

 and Chloride of Gold in Microscopy," in which he calls attention 

 to the use of " Dammar-firniss " by Strieker in place of Canada 

 balsam as a medium with which to mount objects, the more 

 especially histological preparations. And it is remarked that in 

 this, Strieker's, laboratory, as well as in those of Briicke and 

 Eokitansky, this medium has entirely supplanted Canada balsam. 

 Mr. Moseley points out that well-made Dammar varnish possesses 

 several advantages over the microscopist's old friend Canada balsam ; 

 and proceeds to point out that it is " clearer, more free from colour, 

 and when used cold, as it always is, it dries quicker, though it is 

 much thinner and more limpid." He also remarks upon the 

 difficulty of obtaining good Dammar varnish in London, although 

 the gum from which it is prepared is common enough. 



As I have had some experience in the use of this material in 

 microscopy, I will take the liberty of transcribing a paper read by 

 me on this subject before the American Microscopical Society, 

 April, 29, 1865, and which has never been in print as yet. 

 Hereafter I vnR give some of my later acquired knowledge in this 

 connection. The paper is entitled — 



On a New Material for Mounting Microscopic Ohjects. 



" Although I have called the material for mounting microscopic 

 objects, which I am about to describe, new, it may not be so to 

 some of the many students of the microscope ; but, so far as I have 

 been able to ascertain by inquiry among our own immediate 

 members, it has not been as yet brought into use in this country ; 

 and as I am of oj)inion that it possesses in some respects superior 

 characters, fitting it for the special purpose to which I have applied 

 it, to Canada balsam, I venture to bring it to the notice of this 

 Society, hoping that such of our members as will give it a trial will 

 be as well pleased with it and obtain as satisfactory results as I 

 have. 



" I was more particularly drawn to ascertain if it might not 

 be used in mounting microscopic specimens on account of a 

 lengthened series of investigations undertaken for the purpose of 

 ascertaining the improvements accomplished in the manufacture 

 of modern objectives, and the consequent use of such glasses to 

 determine, if possible, the character of the markings to be found 

 upon the silicious cell walls of certain of the Diatomaceae. 



