B L O 



coagulated throughout. After this, the quickfilver regu- 

 larly continued to defcend, Jitid was no longer influenced by- 

 changing the fituation of tiic bulb of the thermometer. 



Witli refpeft to the ufc of the red particle?, Boerhaave 

 fuppofed, that they might tend to keep the diffimilar 

 parts of the bljud incorporated, as (hot aj^itated in a mix- 

 ture of fand ar.d water would prevent the futfidence of the 

 former from the 1 .tter. It feem?, however, no iirprobable 

 opinion, that this is the matter which has the very pecidiar 

 properties of forcibly altradting oxygen gas, even through the 

 medium of the blood vtlFels, and combining with it, and be- 

 coming in conlcqucnce of a fcarlet colour, yet, of iioldingit 

 fo loofely as to part with it in the round of the circulation 

 to carbon and probably to hydrogen, and'thus contributing 

 to the production rjf animal iieat. The writer of the pre- 

 fent article is of this opinion, becaiifc he has expoftd the red 

 parts of the blood to air containing oxygen gaf, ard always 

 found the oxyij-ii gas diminiflitd in proportion to the quan- 

 tity of blood whifth had acquired a fcarlet colour by expofure 

 to it. On the contrary, he has cxpofed the ferum of the 

 blood to funilar kinds of air, and never perceived any abllrnc- 

 tion of oxygen gas bv that fluid. Thus probably we dif- 

 cover the principles of nutrition of the body and the caiife 

 of its heat. For a fur.'her account of the effects of refpiva- 

 t'on on the blood and its confcquences, fee Lungs, ylwc- 

 iloii of. 



Haller's elements of phyfiology may be confulted for an 

 account of all that had been done refpecting the inviftigation 

 of the nature of tl'.c blood till his time ; the works of 

 Mr. Hewfoii and Mr. Hunter m^iy be referred to for addi- 

 tional information on this fuhject ; the works of Fontana, for 

 mierofcopical obfervatlons ; and for novel chemical experi- 

 ments, the writings of Fourcroy, Vauquelin. &c. in the 

 Annales de Chimie, and thofe of Dcyeux and Parmentier in 

 the Journal de Phvfique, and Dr. Thomfon's excellent 

 fummary contained in his Syfliem of Chemii'ry. 

 Blood, t.ansfujionof. SeeTRAssFus os. 

 Blood, injeiling liquors into it. See Injectios. 

 Tjlood, Jpiiting of. See H.emoptysis. 

 Blood, cooling of. Lord Bacon has fuggeflcd that the 

 profecution of experiments on this fubjedl fciight polDbly 

 lead to the means of prolonging liie. But this great philo- 

 .fopher appears to have entertained erroneous notions refpcft- 

 ing the ar.imal economy, on this and fome other points. 

 Nothing accurate was knovrn, in thofe days, on the fubjetl 

 of animal heat. If the blood were cooled below a certain 

 ftandard, difeafe and death, and not longevity, would be 

 the confequence. However, when the quantity of animal 

 heat exceeds what is natural, the excefs is carried off by an 

 ir.creafcd evaporation from tiie furface of the body, in other 

 words, by pcrlpiration. And \n this way, or by the direft 

 application of water of a low temperature to the Ikin, the 

 blood, as well as cvei-y other part of the body, may be faid 

 to be cooled, and difeafe prevented or removed. But this 

 is not what lord Bacon meant in his propolal for cooling 

 the bh>od. 



Blood, Depuration of. See Skcret;on. 

 Blood, Flux of, is called an Haemorrhage. The pe- 

 riodical ones ot women. Menses. Thole alter child-birth, 

 LocHi.i. That ordinarily happening on the firft coition 

 is by fome cnlled arid confidercd as the tell of virginity. 

 ^LOOD, fnuiicl.'ing of. See Styptic. 

 Blood, -voiaiting of. See H.^m.^temesis. 

 Blood, CircuLilion of the. See Circulation. 

 Blood, morlid alterations of. The alterations which the 

 Mood undergoes' in various difeafes, are fuch as claim the 

 attentive obfervation of phyficians. But, iri order to form 

 Vol. IV. 



B L O 



a juft conception of them, it is necefTary previounv to con- 

 fider what are the component parts of this vital fluid, and 

 their relative proportions, in the natural and healthy flate. 



By the accurate analyfes of modern chemifts it has been 

 proved, that, befides water, and various faline rratters 

 (fuch as foda, phofpiiates of lime, of foda, and of ammonia, 

 and muriates of foda and ammonia), the blood confifls of 

 what is termed fibrin, albumen (coagulable lymph), and a 

 colouring principle, viz. oxyd of iron combined with phof- 

 phoric acid. Thefe feveral materials conftitute the fluid 

 called bluod, which, in its natural ftate, is kept in conllant 

 motion, under a temperature of qS'^ or lOo" (in fome ani- 

 mals the temperature is rather higher) of Fahrenheit's 

 thermometer. A large proportion of fibrin, fome albumen, 

 and the colourir.g matter, conftitute the cruor, or craffa- 

 mentuin ; while the ferum is eompofed of w,?ter, with a large 

 proportion of albumen, and the faline fubftanccs above 

 mentioned. 



Now, it is probable, that confiderable alterations take 

 pLicein the relative proportions of th-;fe ingredients, when- 

 ever the living body, whether of man or brute, becomes 

 long or violently difturbed in its action, and cfpecially (as 

 Mr. Hewfon has (hewn) whenever the energy of the vaftular 

 action 13 much iiicreafcd. But in accounting for any re- 

 maikable alterations in the blood, there are feveraf other 

 circumilances, befides that of vafcular action, which require 

 to be noticed ; and particularly the circumftoinces conr.ecied 

 with refpiration, fuch as the temperature, and p'irity or impu- 

 rity of the fuiTounding air, its greater or Icfs degree of hu- 

 midity, &c. Thefe, by their chemical agency, muft have 

 a confiderable influence in the production of the various 

 morbid alterations which take place. 



Many variations, however, in regard to the relative pro- 

 portion of the conftituent parts of the blood, and other 

 chemical changes in its qualities, which in all probability 

 frequently take place, are not obvious to the fcnfes, in fome 

 difeafes, whilft in others they are very confpicuous : for in- 

 ftance, in pleurify, peripneumony, acute rheumatifm, &c. 

 In thefe diforders, the blood drawn from the veins, and 

 fuffered to ftand in the cup uiUil it is cole, becomes covered 

 with a tough buff-coloured coat, or fize, and is ufually called 

 inflamal, or inflammatory ilooil. This fize is formed (fays 

 Mr. Hewfon) by the coagulable lymph (which confills of 

 albumen and a portion of hbrin) being fixed or coagulated, 

 after the red particles have fubfided. The blood in thefe 

 cafes does not appear' to be thicker, but on the contrary- 

 thinner than natural. It is llower in coagulating than 

 healthy blood. The coagulation is owing to the aclioii of 

 the air. Perhaps in pleurify, acute rlu-umatifm, and other 

 diforders belonging to the phlegnialias of nofological writers, 

 fome chemical change is produced in the fibrous matter of 

 the blood (fee Fourcroy, Connoiflanses Cliimiques, article 

 Sang), whereby it is pretcrnaturally foftened or liqnelied ; 

 or there m.ay be an over-proportion of albumen, and that of 

 an altered quality. Whatever be the real chemical diuer- 

 cnce, we cannot think with Mr. Hewfon, that it is wholly 

 occafioned by the increafed force or energy of vafcular 

 action, fince it fometimes occurs in cafes where the aflion 

 of the heart and arteries is not more vigorous than natural, 

 and even where their action appears to be below the natural 

 flandard. Thus a fize has been fometimes obferved upon 

 the blood drawn fit m patients affedled with typhus (Par- 

 mentier and Deyeux in Fourcrov, as above referred to), 

 and even on the blood taken from fcorbutic patients. (Ibid.) 

 And Mr. Hewfon himfelf remarks, that it is a common oc- 

 currence in pregnant women. Increafed energy of vafcular 

 action is doubtlefs a principal caufe of the changes obferv- 

 4 L able 



