ON INJECTING. 269 
There are three well-known methods of making injections, which 
may be distinguished as follows :— 
(1) Injections made with a syringe ; 
(2) Mechanical Injections, in which the function of the syringe 
is replaced by the pressure of a column of water or mercury ; 
(3) Natural Injections; or the introduction of pigments into 
the circulation of living animals. 
The natural method is generally resorted to in cases where the 
two preceding processes are either altogether impracticable or very 
difficult to perform ; as, for example, the filling of the bile ducts 
throughout their course in the liver. 
Injecting by the pressure apparatus is very convenient when 
time cannot be spared to do the work by hand; but the latter 
method is ¢ie one which should be mastered on account of its 
simplicity when once learned, and the ease with which it can be 
performed. 
The substances used for making injections may be divided into 
two classes: one class includes all those which are fluid at the 
ordinary temperature; while the other class includes such as 
become fluid only when heated, and return again to the solid form 
on cooling ; these are called “‘ masses.” 
The following are the most useful injections :— 
PRUSSIAN BLUE FLUID. 
Glycerine... Deana such tert cotae Ale 2m 
Methylated Spirit. icy ddaavtatel, cians ga Buz 
Ferrocyanide of Potassium... ... ... 12 grains. 
sinet., berchloride of Iron ..:,-j<... -....,. .tidrachm: 
Water. cai oe sas 1p AN OZe 
Mix together the glycerine, spirit, “and “water, and divide the 
mixture into two equal parts. In one part, dissolve the Fer- 
rocyanide of Potassium (a), and to the other part add the Tincture 
of Perchloride of Iron (4) ; 6 must now be added very gradually 
to a, the mixture being well shaken after each addition of the iron 
solution. Keep this fluid in a stoppered bottle, and shake it well 
before using it. 
TURNBULL’S BLUE. 
Dr. Beale in his work on the microscope says, “ My friend, Mr. 
B. Wills Richardson, of Dublin, has introduced Turnbull’s Blue in 
preference to ordinary Prussian Blue. Ten grains of pure Sulphate 
of Iron are to be dissolved in an ounce of glycerine, or better 
still, in a little distilled water, and then mixed with glycerine, and 
thirty-two grains of Ferridcyanide of Potassium in another small 
proportion of water and the solution mixed with glycerine. These 
two solutions are then gradually mixed together in a bottle, the 
iron solution being added to that of the Ferridcyanide, and the 
