262 CHAPTER XXI. 



until the curdy precipitate that forms at first lias dis- 

 appeared. Filter through new flannel and keep at 40° C. 

 until injected. 



495. Bruckb's Soluble Berlin Blue (Arch. mile. Anat., 1865, p. 87). — 

 Make a solution of ferrocyanide of potassium containing 217 grms. 

 of the salt to 1 litre of water, and one of 1 part commercial chloride of 

 iron in 10 parts water. Take equal volumes of each, and add to each of 

 them twice its volume of a cold saturated solution of sulphate of soda. 

 Pour the chloride solvition into the ferrocyanide solution, stirring con- 

 tinually. Wash the precipitate on a filter until soluble, dry it, press 

 between blotting paper in a press, break the mass in pieces, and dry 

 in the air. 



The concentrated solution of the colouring matter is to be gelatinised 

 with just so much gelatin that the mass forms a jelly when cold. For 

 another method, see previous editions. 



496. Other Blue Gelatin Masses. — Hoyeb's, Arch. mik. Anat., 

 1876, p. 649; Guignet's, Journ. de Microgr.. 1889, p. 94; Journ. Boy. 

 Mic. Soc, 1889, p. 463 ; Thiersch's, Arch. mik. Anat., i, 1865, p. 148 ; 

 Pol's, Zeit. wiss. ZooL, xxxviii, 1883, p. 494 ; and previoiis editions. 



Other Colours. 



497. Hoyee's Silver Nitrate Yellow Gelatin Mass {Biol. Ccn- 

 tralhl., \\, 1882, pp. 19, 22). — A concentrated solution of 

 gelatin is mixed with an equal volume of a 4 per cent, 

 solution of nitrate of silver and warmed. To this is added a 

 very small quantity of an aqueous solution of pyrogallic 

 acid, which reduces the silver in a few seconds ; chloral and 

 glycerin are added as directed § 489. 



This mass is yellovir in the capillaries and brown in the 

 larger vessels. 



498. Other Colours. — Hoyek's Green {Biol. Centralh., ii, 1882, p. 

 19). Made by mixing a bhie mafs and a yellow mass. Thiebsch's 

 Green (Arch. mile. Anat., 1865, p. 149). Robin's Scheele's Green 

 (Robin, Traite, p. 37). Haeting's White (see Feey, Le Microscope, p. 

 190). Feey's White (*zd). Tbichmann's White (*if?., p.l91). Pol's 

 Brov^n (Zeit. wiss. ZooL, xxxviii, 1883, p. 494). Millbe's Purple (see 

 Aniei: Mon. Mic. Journ., 1888, p. 50 ; Journ. Roy. Mic. Soc, 1888, p. 518). 

 Pol's Lead Chromate (Lehrb., p. 15). Robin's Cadmium (his Traite, 

 p. 36). Thiebsch's Lead Chromate (Arch. mik. Anat., 1865, p. 149). 

 Hoyeb's Lead Chromate (Hid., 1867, p. 136); or, for any of these, see 

 early editions. 



