EXAMINATION AND PRESEEVATION MEDIA. 277 



crown glass by dissolving suitable substances in the glycerin. Thus the 

 refractive index of a solution of chloride of cadmium (CdCl 2 ) * in glycerin 

 may be 1'504; that of a saturated solution of sulphocarbolate of zincf in 

 glycerin may be 1'501; that of a saturated solution of SCHEEING'S J chloral 

 hydrate (in crusts) in glycerin is 1*510 ; that of iodate of zinc in glycerin 

 may be brought up to 1'56. The clearing action of glycerin may thus be 

 greatly increased, and the full aperture of homogeneous objectives brought 

 to bear on objects mounted in one of the above-named solutions. For 

 further details see previous editions. 



425. BARFF'S Boroglyceride (see Journ. Boy. Mic. Soc., 1882, p. 124). 

 This preparation may be obtained (price Is. per bottle) from The Kreo- 

 cliyle Company, Viaduct House, Farringdon Street, E.G., or all wholesale 

 chemists. 



426. Glycerin and Alcohol Mixtures. These most useful 

 fluids afford one of the best means of bringing delicate 

 objects gradually from weak into strong glycerin. The 

 object is mounted in a drop of the liquid, and left for a few 

 hours or days, the mount not being closed. By the evapora- 

 tion of the alcohol the liquid gradually increases in density, 

 and after some time the mount may be closed, or the object 

 brought into pure glycerin or glycerin jelly. 



1. CALBBRLA'S LIQUID (Zeit. wiss. ZooL, xxx, 1878, p. 

 442). 



Glycerin . . . . 1 part. 



Alcohol . . . . .2 parts. 



Water . . . . . . 3 



As already pointed out ( 2), this liquid is in many cases 

 to be preferred to alcohol for keeping fixed objects in until 

 required for dissection or other further preparation. 



2. I strongly recommend the following for very delicate 

 objects : 



Glycerin . . . . .1 part. 



Alcohol . . . . 1 ,, 



Water . . . . . .2 parts. 



3. HANTSCH'S LIQUID. 



Glycerin . . . . .1 part. 

 Alcohol . . . . .3 parts. 

 Water 2 



* Journ. Roy. Mic. Soc., ii, 1879, p. 346. 

 f Ibid., iii, 1880, p. 1051. 

 J Ibid. (N. S.), i, 1881, p. 943. 

 Ibid., p. 366. 



