Phenomena of the Electric and Nervous Itifluences. 37 



bining with either liquids or solids, always sets electricity free, 

 and in the process of respiration a large quantity of oxygen 

 hourly combines with the blood or its carbon ; and there is 

 necessarily an immense quantity of electricity evolved during 

 this action, which, electrifying the blood, is sufficient to pro- 

 duce all the phsenomena I have explained. How far this 

 electricity may be attracted and retained by the brain and 

 spinal chord, may form the subject of subsequent inquiry; but 

 there can be little doubt that the electricity of the living frame 

 is thus derived from the atmosphere, and it is extremely pro- 

 bable that the air expired from the lungs will be found by ex- 

 periment to be highly electrified from the same cause. 



26. The fact of the annihilation, by electricity, of the ad- 

 hesion between solids and liquids, will be found of great value 

 to the practical anatomist in making injections of anatomical 

 preparations. 



27. If the part to be injected is strongly electrified while 

 the coloured liquid is forced into it, the great resistance that 

 in general exists to the passage of the liquid through the fine 

 capillaries will be'overcome, the flu-id will pervade the whole 

 tissue, and the minutest capillaries will be filled in a manner 

 hitherto deemed impossible. 



28. The air-pump is sometimes used to assist the injection 

 of anatomical preparations, and it may be employed in con- 

 junction with electricity; but I believe electricity will be found 

 sufficient without such aid, and I will endeavour to describe 

 the simplest method of thus injecting a part. 



29. Suspend a metallic plate from the ceiling, or any other 

 distant support, by three silken strings, in the manner the 

 pan of a balance is hung; upon this is to be placed the part 

 to be injected with the reservoir of liquid, in order that it may 

 be well insulated, and thus fitted to receive a strong electric 

 charge. The liquid for injection may be contained in an 

 elastic bottle and subjected to a constant pressure by a weight, 

 or it may be in a vessel together with compressed air, the ex- 

 pansion of which will force out the liquid when the channel is 

 open ; or in a reservoir, at a height above the part to be injected, 

 and communicating with it by a pipe. These arrangements 

 I merely throw out as suggestions; an ingenious person will 

 soon contrive his best method of forcing in the liquid. I only 

 impress the necessity of insulating all the apparatus, together 

 with the part to be injected, otherwise it cannot become 

 charged with electricity : the best mode of insulating is to 

 place the whole upon the metallic plate, suspended upon dry 

 silken strings three or four feet long. 



30. When the apparatus, &c. is upon the plate, make a me* 



