CHEMICAL BASIS OF TIIK ANIMAL I'.oDV. 1'LM 



degree the properties of an acid. This view appears to he 

 on the following fads. ( Jxy-ha-moglnhin i- extraordinarily >oluhli> 

 in alkalis and in this solution appear- to he more stable than 

 ordinarily. It i< further slated that it has a feeble j.o\\ 

 facilitating tin- evolution of carbon-dioxide from dilute solutions 



liuni carbonate. 1 It is hence often supposed that in the r.-.l 

 blood-corpuscles the haemoglobin is united to the alkalis of which 

 their stronia partially consists. If the above views are . 

 they may ai>t in explaining to sonic slight extent the diMicultio 

 in undeistanding the causes of the exit of carlioii-dioxide from 

 venous blood during its passage through the lung-. (See 357.) 

 But the possibility here indicated must be received with the 

 greatest caution; for it has been shown that although a dilute 

 alkaline solution of Oxy-hffimoglobiD when exposed to a low 

 partial pressure of carbon-dioxide ah.-orhs le.-< of this gas than 

 sutn'ces to convert the alkali into bicarbonate, thus acting like 

 an acid, at higher partial pressures it absorbs more than can 

 be accounted for by the change of the alkali into bicarbonate. 

 In the latter case the ha^moglobin seems to act like a feeble 

 base. 2 It is interesting here to notice that if the immediately 

 preceding statements hold good. the ha-nioglobin must \ 

 increasingly acid properties in proportion as the carbon-dioxide 

 begins to be evolved from the blood, and might thus further 

 that exit. The power apparently possessed by ha-moglobin of 

 it-df uniting directly with carbon-dioxide will lie referred to 



later on. 



.". Carbon-monoxide haemoglobin. When a ooxnnt oi 



boil-monoxide is pa^-ed through a solution of OXy-h&moglobin the 



n is driven oil' and its place taken by the tirst-nanied ,'as. 

 The compound thn> formed iv>ult<. like OXJ-hflemoglobin, from the 

 union of one molecule of the gas with one of ha-nioglobin. It 

 further resembles oxy-ha-mogloliin in beinu r readily crystallisable :! 

 in forms isoiiiorphous w ith those of the former, but the crystals 

 are on the whole less soluble, brighter coloured and more stable 

 than are tho-e of oxy-hiemoglobin. 4 They are distinctly dichro- 

 matic (see p. L'lfi). The compoinul of carbon-mono\ide with 

 h.cmoglol)in is much more stable than is oxy-ha-moglobin, so that 

 the -as i- not pclled by the action of o\ \ --en. a fact which 



fully explains the fatal result of breathing carbon-monoxide. 

 Finally the spectrum of carbon-nioiio\i.|e ha-ninglohin while 

 similar at first sight to that of oxy-lia-mog|obin. dilli-rs distinctly 



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r |trc|i:iratiiin in ijiiantitv .^T Kill/.. '/J. f. jih', IM \n 



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the action ( )f |i;iin-n'.itii juii'r Bopp^StjrW, IMi '). s in 



