Dr. Spurgin on the Nature and Properties of the Blood. 247 



or variable ratio. The experiments of Gay-Lussac appear to 

 make it constant in a great range of temperature and pressure ; 

 and I have proved from the admitted properties of air, that, 

 when the pressure is constant, the variations of latent heat and 

 temperature, i and t, preserve the same constant proportion, 

 as far as our experience extends. Thus we have (3 z = a t ; 

 and, by substituting in the formula (2), we get. 



This formula is not different from that in p. 252 of this Jour- 

 nal for April last, except in the sign of |3 2 ; and the reason is, 

 that i here stands for the change of temperature produced by 

 the latent heat which is set free, and in the other formula i 

 denotes the variation in the quantity of the latent heat con- 

 tained in the given mass of air. 



What has now been said fully explains the remark I made 

 on the formula of M. Poisson, published in the Coiin. des Terns 

 1826, and proves the justness of that remark. 



Sept. 10, 1827. James Ivory. 



[To be continued.] 



XLII. Outlines of a Philosophical Inquiry into the Nature 

 and Properties of the Blood; being the Substance of three 

 Lectures on that Subject delivered at the Gresham Institution 

 during Michaelmas Term 1826. By John Spurgin, M.D. 

 Fellow of the Royal College of Physicians of London^ and of 

 the Cambridge Philosophical Society. 



[Concluded from p. 191.] 



IIT AVING drawn your attention to this leading property of 

 *--■■ the blood — its fluidity, and illustrated the nature of this 

 property in one respect, that is to say, in its being fitted 

 thereby to traverse every angle and corner of the body ; and 

 having but slightly adverted to, and only indirectly demon- 

 strated, the cause of this its fluidity: we must crave your in- 

 dulgence to permit us to employ the expressions purpose and 

 design as forming a part in our reasoning, in the same man- 

 ner as the algebraist would employ the characters cc,y, ~, to 

 form a part of his analysis, in order that by means of the known 

 values of the other characters he may arrive at the values of 

 those that are unknown. And we crave this indulgence the 

 more confidently, because we do not, as otiiers have done, avail 

 ourselves of the method to discover a proportion between lifeand 

 matter, seeing that there is no proportion between them ; but 



to 



