12 PROPERTIES OF 



to the air, as it would have done without the salt ; but if to 

 this mixture about twice its quantity of water be added, in a 

 short time the whole will be jellied or coagulated, and on 

 shaking the jelly, the coagulum will be broken, and the part 

 so coagulated can be now separated as it falls to the bottom, 

 and proves to be the lymph. 



In these mixtures of the blood with neutral salts, the red 

 particles readily subside, (especially if human blood be used) 

 and the surface of the mixture becomes clear and colourless ; 

 and being poured off from the red part, it is found to contain the 

 coagulable lymph, which can be separated by the addition of water. 



I have tried most of the neutral salts, and have made a 

 table of their effects on the blood; but it is not necessary to 

 trouble the reader with it, as we do not see what use it could 

 be in medicine; for we must not conclude that their effects 

 within the body would be the same as out of it. 1 Indeed, 



1 The salts which keep the blood fluid hy itself, and yet allow it afterwards to jelly 

 on being mixed with water, are, sal Glauberi verus (sulphate of soda) ; sal digestivus 

 Sylvii (chloride of potassium) ', sal communis ; nitrum commune ; nitrum cubicum 

 (nitrate of soda) ; sal diureticus (acetate of potash) ; borax ; the salt made of vinegar 

 and the fossil alkali ; and the salt made with vinegar and chalk. 



The following salts likewise keep the blood fluid, but do not allow it to jelly when 

 mixed with water : Tartarus vitriolatus (sulphate of potash) ; sal Epsomensis ; sal 

 ammoniacus communis; sal ammoniacus nitrosus ; sal rupillensis (tartrate of potash 

 and soda) : but alum, on being mixed with blood, coagulates it immediately (vn). 



(vii.) Dr. Davy a found that various salts and vegetable matters 

 which prevent or retard coagulation, commonly have their influence 

 destroyed by dilution with water ; and lie believes that blood kept fluid 

 by those agents would coagulate in every instance, if the due propor- 

 tion of water were added. He shows that the blood may be preserved 

 either liquid or viscid, by the neutral salts, for days or weeks, without 

 losing the power of coagulating and of contracting when properly di- 

 luted with water ; in the liquid state resisting putrefaction, and yet 

 readily yielding to it after coagulation. Some horse's blood, which I 

 had kept fluid with nitre for fifty-seven weeks, readily coagulated when 

 diluted with water. 



Mr. Prater, too, b supposes that all the neutral salts only suspend co- 

 agulation ; and he has proved that blood which has been kept liquid, 

 either by Epsom salt or carbonate of potass, will coagulate after the 

 addition of certain proportions of water. He suggests, from a trial 

 with muriate of soda, that a small proportion of all the neutral salts 



a Researches, ii, 101-2. 



b Exp. Inq. in Chem. Phys. part i, 8vo, Lond. 1832, pp. 59, 63, 32, 128, 168, 174. 



