270 INJECTIONS. 



Make 



(A) A solution of 1 part gelatin in 2 parts water. 



(B) A solution of 1 part neutral chromate of potash in 11 

 parts water. 



(c) A solution of 1 part nitrate of lead in 11 parts water. 



Mix 4 parts of the gelatin solution with 2 parts of the lead 

 solution, and in another vessel mix 4 parts gelatin solution 

 with 1 part of the chromate solution. Heat both the mixtures 

 to 25 R. ; mix them together with continual stirring until all 

 the chromate of lead is precipitated ; heat over a water-bath 

 to 70 R., and filter through flannel. 



484. Hover's Lead Chromate Gelatin Mass (ibid., 1867, p. 

 136). 

 Take- 

 One volume of a solution of gelatin containing 1 part of 



gelatin to 4 of water. 

 One volume of cold saturated solution of bichromate of 



potash. 

 And one volume cold saturated solution of sugar of lead 



(neutral plumbic acetate). 



Filter the gelatin solution through flannel, and mix in the 

 bichromate solution. Then warm almost to boiling-point, and 

 add gradually the (warmed) sugar of lead solution. Allow 

 the mass to cool down to body temperature, and inject at 

 once. Another mode of preparation is as follows : Mix the 

 sugar of lead solution with part of the gelatin solution, mix 

 the bichromate solution with the remaining gelatin solution, 

 heat the latter mixture, and pour into it the former mixture 

 (gradually), stirring continually. 



If the solutions are mixed at a low temperature a lumpy 

 granular precipitate is formed. Further, when solution of 

 sugar of lead is added to a hot solution of bichromate of 

 potash a rich orange-red precipitate is obtained; whilst if the 

 solutions be mixed cold the precipitate is bright yellow. 



If the solutions of the two salts be kept ready prepared, 

 the injection mass may be mixed in less than a quarter of an 

 hour. Its advantages are that, on account of the extremely 

 fine state of division of the precipitate, the mass is almost 

 transparent, and runs so freely that even lymphatics may be 

 perfectly injected with it, whilst its intensity of colour makes 



