INJECTION. 



[ 351 ] 



INJECTION. 



of water, the whole being afterwards thrown 

 into a large amount of water, and allowed to 

 settle for a few seconds, so that the coarser 

 particles still left may subside; the upper 

 portions of the liquid, containing the finer 

 parts of the powder, are then poured off and 

 allowed to settle, the supernatant water 

 being again poured off, and either allowed 

 to dry slowly, or mixed while moist with the 

 size. 



The ordinary proportions for this injection 

 are 



Vermilion lioz. 1 /* i n\ 

 Si ze ! lb | (Avoirdupois weight). 



or 



Vermilion 164 grs. (Apoth. wt.) 

 Size .... 4 oz, (Avoird. wt.) 



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 ; 

 the oxysulphuret of antimony; solution of 

 carmine in ammonia. 



Yellow 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. 



Acetate of lead 196 grs. 



Bichromate of potash 76 grs. 



Carbonate of potash 41 grs. 



Size 4 oz. 



The chromate of lead prepared from the 



bichromate of potash alone has the deepest 

 colour, and is that generally used. 



No better yellow injection than this can 

 be found, or is requisite. 



White Injection. The best white injection 

 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 gr. 



Size 4 oz. 



286 grs. of carbonate of soda may be substi- 

 tuted for the carbonate of potash. 



Blue Injection. In whatever manner pre- 

 pared, 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 warmed 

 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 around 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 around it 



