INJECTING SMALL VESSELS. 



85 



For 2ied. To a pint of size, add 2 oz. of Chinese vermilion. 

 „ Yellow. „ jj 2|- oz. of chrotne-yellow. 



„ White. „ „ 31. oz. of flake-white. 



„ ^«*e. I, j^ 6 oz. of fine blue smalts. 



It is necessary to remember, that whatever colouring matter is em- 

 ployed must be very finely levigated before it is mixed with the injec- 

 tion. This is a matter of great importance ; for a small lump or mass 

 of colour, dirt, &c. will clog the minute vessels, so that the injection 

 will not pass into them, and the object will be defeated. The mixture of 

 size and colour should be frequently stirred, or the colouring matter 

 will sink to the bottom. Respecting the choice of a proper subject for 

 injecting, it may be remarked, that the injection will usually go fur- 

 thest in young subjects; and the more the fluids have been exhausted 

 during life, the gxeater will be the success of the injection. 



To prepare the subject, the principal points to be aimed at are, to 

 dissolve the fluids, empty the vessels of them, relax the solids, and pre- 

 vent the injection firom coagulating too soon. For this purpose it is 

 necessary to place the animal, or part to be injected, in warm water, 

 as hot as the operator's hand will bear. This should be kept at nearly 

 the same temperature for some time by occasionally adding hot water. 

 The length of time required is in proportion to the size of the part 

 and the amount of its rigidity. Euysch (from whom the art of inject- 

 ing has been called the Ruyschian art) recommends a previous macera- 

 tion for a day or two in cold water. 



The size must always be kept hot with the aid of warm water ; for 

 if a naked fire be used, there is 

 danger of burning it. The size 

 may be placed in a vessel which 

 can be heated by standing it in 

 a common tin saucepan of hot 

 water. A convenient form of 

 apparatus for melting the size, 

 and afterwards keeping it at a 

 proper temperature, is shown in 

 fig. 66. It consists merely of 

 a water-bath, in which the cans 

 containing the injecting fluid 



can be kept hot, and their con- gg 



tents protected from dust by 

 means of their covers. A small apparatus of this kind could be 



