236 INJECTION 



needful quantity of neutral carmine staining solution {loc. cit., 

 p. 17). Digest in a water-bath until the dark violet-red colour 

 begins to pass into a bright red tint. Then add 5 to 10 per cent, 

 by volume of glycerin, and at least 2 per cent, by weight of 

 chloral, in a concentrated solution, and strain. 



525. Fol's Carmine-Gelatin Mass {Lehrb., p. 13). This can be 

 kept in the dry state for an indefinite length of time. 



Gelatin in sheets is cut into strips which are macerated for 

 two days in carmine solution (prepared by diluting one volume 

 of strong ammonia with three of water and adding carmine to 

 saturation, and filtering after a day or two). The strips are then 

 rinsed and put for a few hours into water acidulated with acetic 

 acid, then washed on a sieve for several hours in running water, 

 dried on parchment paper, or on a net, and preserved for future 

 use. To get the mass ready for use, the strips are soaked for an 

 hour in water and melted on a water-bath in 10 to 20 parts of 

 water. 



For another process, which is said to give somewhat better results, 

 but is more comphcated, see loc. cit., or Zeit. iviss. Zool., xxxviii, p. 492, 

 or previous editions. 



526. Krause's Carmine-Gelatin Mass (Zeit. iviss. Mik., xxvi, 1909, 

 p. 1). 100 grm. gelatin soaked in water, put for two to three days into 

 a solution of 15 grm. carmine in 2 litres of water with 100 grm. of borax, 

 washed, treated for a short time with hydrochloric acid of 2 per cent., 

 washed, melted and preserved with camphor. 



527. Other Carmine- Gelatin Masses. Thiersch's, see Arch. mik. 

 Anat., 1865, p. 148. Gerlach's, see Ranvier, Traite, p. 118, Carter's, 

 see Beale, p. 113. Davies, see his Prep, and Mounting of Mic. Objects, 

 p. 138. 



BLUE GELATIN MASSES 



528. Ranvier's Prussian Blue Gelatin Mass {Traite, p. 119). 

 Make a concentrated solution of ferric sulphate in distilled 

 water, and pour it gradually into a concentrated solution of 

 yellow prussiate of potash. There is produced a precipitate of 

 insoluble Prussian blue. Wash this on a felt strainer, under- 

 neath which is arranged a paper filter in a glass funnel, for some 

 days, until the liquid begins to run off blue from the second filter. 

 The Prussian blue has now become soluble. The strainer is 

 turned inside out and agitated in distilled water ; the Prussian 

 blue will dissolve if the quantity of water be sufficient. 



The solution may now be injected just as it is, or it may be 

 kept in bottles till wanted, or evajiorated in a stove, and the 

 solid residuum put away in bottle. 



For injections, if a simple aqueous solution be taken, it should 

 be saturated. Such a mass never transudes through the walls of 

 vessels. Or it may be combined with one-fourth of glycerin, or 

 with one twenty-fifth of gelatin soaked for an hour in water and 

 melted over a water-bath in the water it has absorbed. The 



