50 DR. R. ANGUS SMITH ON THE EXAMINATION 



Chester. In the first case^ as well as in the second and 

 similar cases^ the amount of oxygen is too great to allow 

 of putrefaction; and in the third case it was very clear 

 that the oxidation was a process of decolorization, at least 

 in part, whatever else may have occurred. This decoloriza- 

 tion is caused by the oxidation of the humus and its 

 removal as carbonic or other acid. 



Another important feature in putrefaction is the occur- 

 rence of carburetted hydrogen. The carbonaceous or 

 organic compound, having lost the ties that bound it 

 together, is broken up into fragments. The carbon, 

 when it can find oxygen, goes off in its company, but 

 otherwise it leaves with hydrogen; separate, however, it 

 must, and that with considerable violence. When there 

 is a great amount of oxygen these decompositions of 

 organic matter do not take place; and if the Loch- 

 Katrine and other water were largely supplied with 

 organic matter, putrefaction would be entirely absent, as 

 it now is, as long as the high amount of oxygen was kept 

 up in continual presence. 



That organic matter does exist in peaty water to a 

 larger extent than in streams not peaty, but still offensive, 

 may be taken for granted. A very brown water contains 

 about four grains per gallon. It is extremely dark, indeed, 

 if there are six ; but in the one case putrefaction, or, w^hat 

 is still worse, the development of mischievous germs, may 

 occur, whilst in the other they are stifled. How far this 

 disinfecting and preserving quality of peaty matter will 

 act in weak solutions I cannot tell; but in its greatest 

 strength (that is, surrounded by the matter of the peat 

 itself), preservation may exist for an indefinite time ; and 

 the non-occurrence, of putrefaction in weaker solutions 

 may be considered sufficient to show that there is abundant 

 preserving-power for the amount of matter to be preserved 

 in these waters. 



