ZOOLOGY AND BOTANY, MICROSCOPY, ETC, 909 



B. Vesuvin celloidin. 1. Make a saturated solution of vesuvin in 

 absolute alcohol. 



2, Dissolve in this pieces of celloidin until the desired consistency 

 is reached. 



C. Opaque ceUoidin. 1. Dissolve celloidin in absolute alcohol and 

 ether in equal parts. 



2. Add vermilion or prussian blue. 



Mounting in Cells with Canada Balsam.* — Mr. H. Sharp de- 

 scribes a method which obviates many of the difficulties usually 

 experienced. 



A cell of paper or card of the requisite thickness is cemented on 

 the slide with gum, and a small piece cut away on opposite sides of 

 the ring. 



The object (which has never been allowed to dry, but has been 

 transferred from the medium in which it was arranged, into strong 

 spirit and thence into oil of cajeput, into benzine and finally into tur- 

 pentine) is next placed in the centre of the cell with a single drop of 

 turpentine on it to keep it moist, and the cover-glass is put on the 

 gummed surface of the cell. When the gum has set and the cover is 

 quite firm a little benzine is taken up with a pipette and applied to 

 one of the openings cut in the card cell, when the benzine instantly 

 runs in and fills up the cell, and in a few minutes the card is thoroughly 

 soaked with it without any efiect on the gum. The benzine is then 

 all drawn away with blotting-paper, and balsam applied to one of the 

 openings. When the slide is gently warmed, this soon fills the cell 

 and shows freely at both openings. When the balsam is sufficiently 

 hardened the slide is put on the turntable and trimmed up, leaving a 

 ring of balsam. The final finishing touch is done by holding the 

 slide, cover side down, and giving it a circular sweep over a flame so 

 that the latter just touches the balsam ring all round for an instant, 

 leaving it as even and smooth as glass. 



A great advantage of the method is claimed to be that when once 

 the cover is in its place and the gum has set there is not the least 

 danger of the cover shifting or the object being displaced when finish- 

 ing and cleaning the slide. 



Monobromide of Naphthalin and Tribromide of Arsenic. — 

 Dr. C. V. Zenger finds that a concentrated solution of tribromide of 

 arsenic in monobromide of naphthalin has a mean refractive index 

 of 1 • 72, nearly approaching the index of the tribromide itself (1 • 78).| 



The author says that the " aspect of Diatomaceaj mounted in 

 this substance is simply surprising both as regards the crispness of 

 the images and the amount of light received from the more minute 

 details of the valves." 



Mayer's Carbolic Acid Shellac. J — Finding that clove oil and 

 creosote produce tine granulations wlien used in the ordinary shellac 

 method, Dr. P. Mayer has adopted a new method of dissolving the 



• Journ. and Proc. Roy. Roc. N.S. Wulea, xvi. (1883) pp. 28G-8. 

 t Sco also this Journal, ante, p. 377. 

 i Amer. Ndtural., lix. (1885) p. 73.-J. 



