ON MINUTE INJECTIONS. 163 



or fourth part of the whole, should be very fluid, so as to be 

 capable of penetrating the smallest vessels ; afterwards the 

 thicker or coarser portion should be thrown in so as to push the 

 first before it. 



As the method of injecting the 'minute capillaries with 

 colored size is often attended with doubtful success, various 

 other plans have been proposed. Ruysch's method, according 

 to Rigerius, was to employ melted tallow, colored with vermi- 

 lion, to which, in the summer, a little white wax was added. 



Mr. Rauby's material, as published by Dr. Hales, was resin 

 and tallow, of each two ounces, melted and strained through 

 linen ; to which was added three ounces of vermilion, or finely 

 ground indigo, which was first well rubbed with eight ounces of 

 turpentine varnish. 



Dr. Monro recommended colored oil of turpentine for the 

 small vessels, after the use of which he threw in the common 

 coarse injection. 



Professor Breschet frequently employed with success milk, 

 isinglass, the alcoholic solution of gum-lac, spirit varnish, and 

 spirit of turpentine; but he highly commends the coloring 

 matter extracted from campeachy, fernambouc, or sandal woods. 

 He says, "The coloring matter of campeachy wood easily dis- 

 solves in water and in alcohol; it is so penetrating that it be- 

 comes rapidly spread through the vascular networks. The sole 

 inconvenience of this kind of injection is, that it cannot be 

 made to distend any except most delicate vessels, and that its 

 ready penetration does not admit of distinguishing between 

 arteries, veins, and lymphatics." He also recommends a solu- 

 tion of caoutchouc. 



Another process, which may be termed the chemical process, 

 was published in the Comptes Rendus, 1841, as the invention of 

 M. Doyere. though the credit of first suggesting it is due to Dr. 

 Goddard, of Philadelphia. According to this, an aqueous solu- 

 tion of bichromate of potass is propelled into the vessels; and 



