ON THE BONES OF ANIMALS. 42 J 



indeed, if it be in large proportion, it communicates a fenfi- 



bly red tinge. But there is always preftnt in the blood, and in —formed as it 



afiate of lUution in the fhrum, a quantity of the earthy matter of ^^^^^^ before the 



, , , , ^ ,. J 7 J ^ 7 7 • offeous depofi- 



tne bones, pnofpnate of lime, ready to be aepojitea, as the exigen^ tion. 



cies of the anwial may require. Now the phofphate of lime is an 

 excellent mordent to madder, and has a ftrong affinity to it, and 

 is confequently admirably fiited to afford a hafe for the colouring 

 matter oj it : in fuck experiments, therefore, they concrete in the 

 fiate of a bright red lake, whence the colour of the bones is derived. 

 That this is adually the cafcj may be (hewn by a variety of 

 experiments. Thus, if lo an infufion of madder in diftilled 

 water, be added a little of the muriate of lime, no change is 

 perceived: but if to this mixture be added a folution of the 

 phofphate of foda, immediately a double elective altra6tion 

 takes place. The muriatic acid combining with the foda, re- 

 mains fufpended, or diflblved in. the water ; whilft the phof- 

 phoric acid, thus deprived of its foda, combines with the Jime 

 which the muriatic acid parted with, and forms phofphate of 

 lime or earth of bones. This fubftance, however, being in- 

 foluble in water, falls to the bottom ; but having combined at 

 the inftant of its formation with the colouring matter of the 

 madder, they fall down united into a crimfon lake ; precifely 

 of the fame tint with that of the bones of young animals, 

 which have been fed with madder. From this fimple reprc- 

 fentation of the matter, we have a ready explication of every 

 circum (lance which has been remarked as extraordinary re- 

 fpeding this fubject." 



Whilft Dr. Rutherford thus gives a raoft fatisfadory expla- Dr. Rutherford 

 nation of the colour of madder being communicated to the ^^,^'"^•"^^^3^^" j'g_ 

 bones alone, of all the white parts of an animal ; we ^nd that pofuion. 

 he embraces the fame opinion as other phyliologifts, that the 

 ©(Teous materials acquire their colour previous to their depo- 

 fition, whilil in a ftate of folution or mixture in the blood j 

 from whence they are afterwards depofited, and concrete in 

 the form of a bright lake. In no part of his ingenious re- 

 marks does he hint at the probability that the bones already 

 formed in an animal, may, during the ufe of madder, become 

 red, and after its difufe gradually refume their natural colour, 

 by the agency of a power entirely independent of their depo- 

 fition and abforplion : that this is probable I ftiall now proceed 

 ^0 prove. 



Before 



