INJECTION. 



[ 424 ] 



INJECTION. 



and either allowed to dry slowly, or mixed 

 while moist with the size. 



The ordinary proportions for this injec- 

 tion are : 



Vermilion 1^ oz., Size 1 lb., or 

 Vermilion 164 grs., Size 4 oz. 



Stir the colouring-matter well with the 

 warmed size, then strain. 



Other red colouring-matters have been 

 used, but they cannot be recommended. 

 Among them may be mentioned : the basic 

 chromate of lead, prepared by boiling the 

 neutral chromate with caustic or carbonate 

 of potash ; the biniodide of mercury, formed 

 by decomposing bichloride of mercury with 

 iodide of potassium in atomic proportions ; 

 and the oxysulphuret of antimony. 



Yelloio Injection. This is prepared with 

 the chromate of lead (chrome-yellow), as 

 follows : 



Take of 



Acetate of lead 380 grs. 



Bichromate of potash 152 grs. 

 Size 8 oz. 



Dissolve the lead-salt in the warm size, 

 then add the finely powdered bichromate of 

 potash. 



As thus prepared, some of the chromic 

 acid remains free, and is wasted, which may 

 be obviated by preparing the chromate of 

 lead with the chromate of potash in the 

 proportions of 



Acetate of lead 190 grs., 



Chromate of potash (neutral) 100 grs. 



Size 4 oz. 



or 



Acetate of lead 196 grs. 



Bichromate of potash 76 grs. 



Carbonate of potash 41 grs. 



Size 4 oz. 



Thiersch used chromate of potash and 

 nitrate of lead. 



The chromate of lead prepared from the 

 bichromate of potash alone has the deepest 

 colour, and is that generally used. 



White Injection. The best white injec- 

 tion is made with carbonate of lead, thus : 

 take of 



Acetate of lead 190 grs. 



Carbonate of potash 83 grs. 



Size 4 oz. 



Dissolve the acetate of lead in the warm 

 size and filter; dissolve the carbonate of 



potash in the smallest possible quantity of 

 water, and mix it with the size. 



143 grains of carbonate of soda may be 

 substituted for the above amount of carbo- 

 nate of potash. 



A white injection (very inferior) may also 

 be made with carbonate of lime, by taking 

 of 



Fused chloride of calcium .. Ill grs. 



Carbonate of potash 167 grs. 



Size 4 oz. 



28G grs. of carbonate of soda may be substi- 

 tuted for the carbonate of potash. 



Blue Injection. In whatever manner 

 prepared, this cannot be in general recom- 

 mended ; for blue pigments reflect so little 

 light, that the injections made with them 

 appear almost black. The only one worthy 

 of mention is prussian blue suspended in 

 oxalic acid, which may be prepared with 



Prussian blue 73 grs. 



Oxalic acid 73 grs. 



Size 4 oz., 



the oxalic acid being first finely triturated 

 in a mortar, the prussian blue and a little 

 water afterwards added, and the whole 

 then thoroughly mixed with the previously 

 wanned size. 



General method. When the part for 

 injection has been selected, the first pro- 

 ceeding is to fix the pipe in some vessel; and 

 the larger this is, the more easily will the 

 pipe be inserted and fixed. When the vessel 

 has been isolated, if it has been cut across, 

 the pipe should be introduced at its end, 

 pushed up as far as possible, and a piece of 

 not too thin silk thread passed beneath and 

 tied around it, enclosing of course the nozzle 

 of the pipe ; the ends of the silk should then 

 be wound round the arms of the pipe and 

 again tied, so that the pipe may remain 

 firmly fixed in the vessel. If the vessel be 

 not divided, a longitudinal slit should be 

 made in it for the introduction of the pipe, 

 the thread being passed round it by a 

 curved needle, the eye of which carries the 

 thread. As soon as the pipe has been fixed 

 in the vessel, all other vessels communi- 

 cating with it should be tied round with 

 silk thread or closed in some other way, that 

 the injection may not escape : sometimes it 

 is requisite to enclose a part of the tissue 

 itself in the ligature ; in other instances 

 their closure may be effected by fusion of 

 the tissue at the spot from which the injec- 

 tion might escape, by the application of a 

 red-hot iron. 



