TECHNOLOGY OF DIATOMS. 271 



Nahire of Moiwbroinide of Naphthaline and Catiada Balsam. — 

 The Monobromide of Naphthaline is a Hquid, very fluid, of a 

 golden yellow when pure, very subtle, and very penetrating. Its 

 index of refraction is i"65. In mixture with Canada balsam it 

 constitutes a medium of a clear and agreeable colour, and still 

 possessing an index of i"62, which is equal to styrax. 



The mixture is made by adding one volume of Canada balsam, 

 very thick and very pure, to an equal solution of Monobromide of 

 Naphthaline. They are agitated from time to time to cause an 

 intimate union of the two, which then form a semi-fluid of a very 

 clear yellow. 



The use of this mixture for the mounting of Diatoms requires 

 certain observations and certain precautions : 



I. — It is absolutely necessary that the vessels in which the 

 mixtures are made, and in which they are kept, should be kept 

 absolutely free from all traces of moisture, and hermetically sealed, 



2. — At the moment of mounting, which is done in the same 

 way as with the other media, it is needful to pass the slip and cover 

 rapidly over the flame of a spirit lamp to drive off all moisture. 



3. — The mixture cannot be hardened without losing, in great 

 part, its index of refraction, by the evaporation of a part of the 

 Monobromide. These preparations should be allowed to dry 

 spontaneously in the open air for some days, or for some hours in 

 a stove from 30 to 4o°C, after which the cover should be sealed 

 down with two or three coats of lac cement. 



The Mysteries of Flowers. — One of the most mysterious 

 elements of flowers is the perfume, the essential action of which 

 in plant-life cannot be demonstrated by the wisest of our scientific 

 men. Gas can be weighed, but not scent. The smallest-known 

 insect that lives in the heart of the Rose can be caught by a 

 microscope lens and made to give up the secret of its organisa- 

 tion ; but what it is that the warm summer brings us Irom the 

 wild flowers of the hillsides or wafts to us from the choice plants 

 of the hothouse no man has been able to determine. So fine, so 

 subtle, so imponderable, it eludes weights and measures. — Journal 

 of Horticulture. 



