358 SUMMAKY OP CURRENT RESEARCHES RELATINa TO 



phosphorus, as the latter is not perfectly soluble in oil of cassia as in 

 carbon bisulphide. A ring of liquid glue should be made on the 

 slide, and allowed to dry, drying the diatoms on the cover, adding 

 the solution, and quickly inverting the cover in its place, then 

 removing the surplus squeezed out by blotting-paper, carefully pressing 

 down on the glue ring, and then sealing with balsam. The solution 

 smokes on exposure to the air, but in these preparations there is no 

 evidence of acid flakes. 



On endeavouring to make a good solution of sulphur in carbon 

 bisulphide, it did not appear that sufficient dissolved to get the full 

 benefit of the high index of sulphur. He therefore sought a better 

 solvent, and found it in anilin. On making a test mount of mixed 

 diatomaceous material he was surprised at the brilliancy and sharp- 

 ness of definition, in which it excels any other medium yet tried. 

 The diatoms used were in alcohol. He first placed the required 

 quantity on the inverted cover, dried them, added sufficient medium to 

 cover them, heated the cover to drive the air out of the cavities of the 

 diatoms and cause the fluid to enter, added, if necessary, a little 

 more, inverted in place on the slide on a turn-table, and removing 

 any surplus by a blotter, put a ring of balsam or shellac cement 

 round, thus finishing at one operation. The anilin is not very 

 volatile, and the adhesion of the cover very slight, but with care, 

 using a long-bristled brush and thin balsam, a coat can be got quite 

 sufficient to seal and fix the cover in place, and additional coats may 

 be given when convenient. 



Anilin, according to Storer, dissolves its own weight of sulphur ; 

 if heat is used it will become supersaturated, and crystals will form 

 on the slide, which are very pretty of themselves, but of course are 

 not desirable with other objects. As Gladstone and others have 

 indicated that high refractive power accompanies complex molecular 

 constitution, it is probable the best solvents for this purpose will be 

 found among the carbon compounds like anilin, chinolin, &c. 



Black Ground for Opaque Mounts.* — Mr. W. C. Brittan thinks 

 that the following receipt for a paint that will give a dead black 

 surface as required for the inside tubes of optical instruments, &c., 

 should be in the hands of all who work with the Microscope : — Take 

 two grains of lampblack, and add three drops of gold-size, mix 

 thoroughly, and add 24 drops of turpentine, when again thoroughly 

 mixed it is ready for use. Apply it thin with a camel's hair brush. 

 When dry, the articles will have as fine a dead black as when they 

 came from the optician's hands. This paint will also be found 

 just the thing where a dead black ground is required for opaque 

 mounts. 



Exhibiting the Streaming of Protoplasm.t — The streaming 

 motion of protoplasm can be exhibited very satisfactorily, according to 

 Mr. T. J. Burrill, in the thin membrane (upper epidermis of scale- 

 leaf) found between the scales of the bulb of the common onion. All 

 that is necessary to do is to transfer a piece of the fresh membrane, 



* The Microscope, vi. (1886) p. 41. f Bot. Gazette, x. (1885) pp. 428-9. 



