ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 1097 



Eau de Javelle for Clearing.* — Prof. E. Strasburger caHs atten- 

 tion to Eau de Javelle f as a medium for rendering vegetation-points 

 clear. 



Eau de Javelle (liypocLloiite of potash) is decidedly superior 

 to Eau de Labarraque (hypochlorite of soda). It is made by mixing 

 20 parts of the officinal (25 percent.) calcium chloride with 100 parts 

 water: after standing some time, a solution of 15 parts jiotash in 100 

 vater is added, and after standing some days longer it is filtered. 

 Should the solution be found to contain too much lime, add a few 

 drops of potash and filter off precipitate. 



Fixing Objects to the Cover-glass. J— Mr. C. Van Brunt gives one 

 of many methods of fixing objects to the cover-glass which has been 

 used very successfully in glycerin mounts — the albumen method. 

 Mix filtered or strained albumen and glycerin in equal j^arts, and with 

 a needle apply a thin film of the mixture to the surface of the cover- 

 glass. On this film place the object. If now the albumen is coagu- 

 lated by a gentle heat it will hold the object so fast that it can be 

 mounted in glycerin, and will always keep its place. The albumen 

 is transparent, except when too much is used. 



Smith's Mounting Media of High Refractive Index.§ — At the 

 Meeting of the American Society of Microscopists at Cleveland, 

 Prof. H. L. Smith described his process of mounting in media of 

 high refractive index, and gave the formulae for preparing the same. 

 The white medium, which has a refractive index of about 1 •?, is very 

 easily prepared, and is pronounced by Prof. Smith and those who 

 have used it, as unchangeable, provided moisture is kept out. The 

 following is the formula as given for this : — 



A stiff glycerin-jelly is first made, about the consistency of honey, 

 by dissolving clear gelatin (Cox's) in pure glycerin, by aid of heat, 

 and in two fluid drams of this, 40 gr. of pure stannous chloride aro 

 dissolved. The solution is easily aflFected by a little heat. When 

 this solution is made it will probably be somewhat milky, but by 

 boiling it in a test-tube it w^ll become beautifully clear and about 

 the colour of balsam. This boiling must bo done in a test-tube not 

 over one-fourth full, as the bubbles are, towards the last, very largo 

 and thrown violently up and liable to eject the fluid from the tube ; 

 but with care the whole may in a short time be made not only clear, 

 but when cold about as stiff as thick balsam, and, if in a small vial, it is 

 not readily poured out. This medium should be used in making mounts 

 precisely as balsam is when the mounts are to be finished by heating. 

 The bubbles escape very rapidly and easily, but towards the end of 

 the boiling, as the medium becomes viscid, thoy are inclined to persist, 

 but }>y carefully heating, using a small flame, they will disappear, 

 and indeed, as they arc mostly steam, they will frequently di6api)car 



• Bot. Ccntmlbl., xxiv. (188.5) p. lo7. 



t Hf* tliifl Jfinninl, ontc, p. 89;{. 



I Journ. N. York Mirr. Soc, i. (188r)) pp. l.'iS-n. 



§ Amcr. Mod. Micr. .Jomn., vi. (188.'); pp. 101-:< (1 lig.). 



