24 SALIVA. 



in this fluid, both by dry distillation of the residue of the saliva, 

 and by the simple application of an extremely small pair of plates 

 of copper and zinc to the slightly acidified saliva. There are many 

 reasons why, even when much mercury had been taken into the 

 organism, none was found in the saliva ; in the first place, it has 

 very often been only buccal mucus which has been examined, for 

 we may readily convince ourselves by the microscope, and more 

 accurately by chemical analysis, that at the commencement of 

 salivation scarcely any saliva is found in the sputa ; the salivary 

 glands are as yet not affected ; the expectoration consists almost 

 entirely of whole patches of [epithelium and of mucus from the 

 tonsils ; and in products of this nature I have never been able to 

 detect any mercury, even after its free administration; and, 

 secondly, it has been forgotten by some experimentalists, that 

 mercury volatilizes very readily with the vapour of water, so that, 

 by evaporating too rapidly, and without sufficient care, they have 

 allowed the little mercury that was present to escape* 



Wright has injected alkaline carbonates into the veins of 

 animals, and has found a consequent augmentation of the alkali 

 in the saliva 5 when, on the other hand, he injected acetic acid or ex- 

 tremely diluted sulphuric acid into the vessels of healthy animals, 

 he never found that an acid reaction of the saliva was induced. 



It is singular that dogs into whose jugular veins Wright 

 injected four ounces of pyroligneous acid, and half a drachm of 

 sulphuric acid (although the acids were diluted with four and six 

 ounces of water), bore this outrage so well, that after a short time 

 they quite recovered,* and Wright found that their saliva had 

 returned to its alkaline reaction. In cases in which I have per- 

 formed similar experiments on animals, although for a different 

 object, death was the invariable result an event which may be 

 very easily explained, since stasis must be very rapidly induced in 

 the pulmonary capillaries, in consequence of the coagulation or 

 gelatinising of the blood. 



We have referred in the first volume to the incidental occur- 

 rence of sugar (p. 289) and of lactic acid (p. 94) in the saliva. 

 It is extremely difficult to decide whether actual albumen coagu- 

 lable by heat is present in a specimen of saliva. 



Wright assumes that there are two different kinds of albu- 

 minous saliva, and as we have no experience on the point, we 



* [This is hardly correct. The dog into whose vein the pyroligneous acid 

 was injected, died in about a week. See the "Lancet," 1842-3, vol. ii. p. 189. 

 G. E. D."| 



