HOYER'S SOLUBLE BERLIN BLUE GELATIN MASS. 227 



(c.) To the latter mixture add first 24 c.c. of the oxalic - 

 acid solution, stir well, and then add the gelatin and iron 

 mixture (A) . Stir continually, keeping the temperature at 

 from 20 to 25 R. until the whole of the Prussian-blue is 

 precipitated. Finally, heat over a water-bath to about 70 

 R. and filter through flannel. 



453. Fol's Berlin Blue Gelatin Mass (Zeit.f. wiss. ZooL, xxxviii, 

 1883, p. 494). A modification of Thiersch's formula, No. 

 452. 120 c.c. of a cold saturated solution of sulphate of iron 

 are mixed with 300 c.c. of the warm gelatin solution. In a 

 separate vessel 600 c.c. of the gelatin solution are mixed with 

 240 c.c. of a saturated solution of oxalic acid, and 240 c.c. of 

 a cold saturated solution of red prussiate of potash are added 

 to the mixture. The first mixture is now gradually poured 

 into the second, with vigorous shaking, the whole is warmed 

 for a quarter of an hour over a boiling water-bath, the mass is 

 allowed to set, is pressed out into strings through tulle or 

 netting, as described for the carmine mass, supra, 446, and 

 the strings are washed and spread out to dry on the prepared 

 paper. (It is necessary to dry the strings without remelting 

 in this case, because the mass does not readily melt without 

 the addition of oxalic acid.) In order to prepare the mass 

 for injection, the strings are put to swell up in cold water, 

 and then warmed with the addition of enough oxalic acid to 

 allow of complete solution. 



454. Hover's Soluble Berlin Blue Gelatin Mass (Arch. f. mik. 

 Anat., 1876, p. 649). The filtered and not too much washed 

 precipitate of soluble Berlin blue is brought in a little water 

 on to a Graham's dialyser, and the external water changed 

 until the solution begins to pass through the parchment. 

 Dilute the solution and filter through filter-paper, an operation 

 which becomes easy after dialysis. The solution may be 

 injected pure (for lymphatics, for instance) or may be com- 

 bined with gelatin. To do this, warm the solution almost to 

 boiling-point, and add gradually a warm, thin solution of 

 gelatin until coagulation begins to set in. Strain through 

 wetted flannel. 



