MICROSCOPICAL TECHNIQUE. 296 



a red violet. In all cases, where possible, for the sake of absolute 

 certainty, the urine should be tested for glucose by any of the 

 well-known reactions."— iVrt;//^;/^/ Druggist. 



Fixer for Vegetable Tissues.— Zenker uses the following liquid 

 in the fixation of vegetable tissues for microscopical examination : 

 Mercury Bichloride ... lo parts. 



Potassium bichromate ... .. 5 >> 



Sodium sulphate ... ... ... 2 ,, 



Salicylic acid, in crystals ... ... 10 ,, 



Distilled water ... . . ... 200 „ 



The liquid penetrates and fixes the tissue with great rapidity 

 and sureness. — National Druggist. 



Separation of Diatoms, etc., from Sand. —The Zeitschrift filr 

 Angewandie Mikroskopie says : — " For this purpose we use certain 

 liquids of high specific gravity, such as are used in mineralogical 

 operations, and we commend the following : — 



Brown's Liquid. — Methylene iodide, which has a specific 

 gravity of T^'2i- By adding iodoform to this, this figure is raised to 

 3'45, while iodine increases it to 3*65. 



Klein's Liquid. — Potassium-boro-wolfranin, the specific gra- 

 vity of which is 3*28. 



Rohrbach's Liquid. — Barium-mercury-iodide, s.g. 3*58. 



Toulet's Liquid. — Sodium-mercury-iodide, s.g, 3*19. 



Other liquids are : — Silver iodide dissolved in a concentrated 

 solution of silver nitrate, which makes an oily, brown liquid of 

 s.g. 5"o; thallium-silver nitrate, melting at 75*^C., s.g. 4*1. Con- 

 cerning this last-named chemical, the Bayerische Industrie und 

 Gewerbeblatt has the following information : — 



" The specific gravity and the melting point of thallium-silver 

 nitrate fall as the proportion of thallium nitrate is increased ; thus, 

 while the latter substance has a specific gravity of 5 '00, and a 

 melting point of 250^, the addition of i part of silver nitrate to 

 4 parts of the thallium salt decreases the melting point to 2oo^C., 

 and the specific gravity to 4*9. Three parts of silver nitrate to 

 4 parts of thallium nitrate bring the specific gravity down to 47, 

 and the melting point to loo^C. 



