INJECTION APPARATUS. 165 



first escapes through the pores of the flannel ; allow 

 the solutions to drain off; pour a little distilled 

 water very carefully over the blue mass, returning 

 the first washings if colored, and renew the water 

 from day to day until it drips through permanently 

 of a deep blue color. This is a sign that the salts 

 are washed away, and all that is further necessary 

 is to collect the pasty mass from the strainer and 

 allow it to dry. 



Apparatus employed for injecting. This con- 

 sists, in the first place, of a bottle for holding the 

 colored fluid ; and secondly, of some means of pro- 

 ducing a steady, elastic, and readily alterable pressure 

 on the surface of the fluid so that it may be driven 

 with any required force into the arteries. The 

 method formerly employed of forcing the injecting 

 material from a small syringe directly into the 

 bloodvessels has been almost entirely given up, 

 on account of the impossibility of estimating the 

 amount of pressure which is being exerted, leading 

 often to the employment of too great a pressure and 

 the consequent rupture of some of the smaller blood- 

 vessels. Fig. 28 represents a convenient form of 

 apparatus for general use. The bottle (i), 1 which 

 holds the injecting fluid, is a moderate-sized, wide- 

 mouthed phial, with a well-fitting vulcanized India- 

 rubber cork, through which two glass tubes pass. 

 One of these goes to the bottom, and from it an 

 India-rubber tube passes, which will be subsequently 

 connected with the artery canula (c), but not before 

 this has been inserted in the bloodvessel, in the 

 manner immediately to be described. The other 

 passes only just through the cork, and serves to 

 maintain communication by means of another India- 

 rubber tube, with the pressure-bottle p. The injec- 

 tion-bottle is placed during the process of injecting 

 in a large beaker (b) of warm water (about 40 C.) ; 

 a piece of cork is wedged in between the bottle and 



1 A simil .r one is better shown in Fig. 30, at c. 



