460 



Mr. W. North. The Influence of 



mass, which was occasionally removed very carefully to a mortar and 

 broken up, in order to hasten the process. The products were sepa- 

 rated into three lots, as above stated, and stored in a well stoppered 

 bottle till the analysis could be made. The total amount of dry 

 matter yielded by the f aeces was determined, and the calculation of 

 the analyses made from this. 



The nitrogen was estimated by the soda4ime process, the material 

 being reduced to an exceedingly fine powder, and burned in an iron 

 tube 3 inches longer than those used for the urine, in order to secure 

 the complete decomposition of any undigested albuminoids which 

 might be present. 



Phosphates were estimated after partial incineration in a platinum 

 capsule by the magnesia method, and weighed as pyrophosphate. 



Chlorides. — The precipitate yielded on addition of a few drops of 

 argentic nitrate to a watery extract of the dry material rarely 

 amounted to more than a perceptible cloudiness, and consequently no 

 figures appear in the analyses. 



Sulphates. — The same is still more true of the precipitate yielded by 

 the addition of barium nitrate and hydrochloric acid to the same 

 solution. It was often an open question whether there was any pre- 

 cipitate at all, so small was the quantity of soluble sulphate present. 

 This led me to consider in what form the sulphur might exist, and in 

 the light of Lepine's experiments on the sulphur in the urine, I was 

 led to try the effect of powerful oxidising agents on the sulphur 

 compounds which might be present, and I very soon found that 

 nothing short of combustion in a stream of oxygen would completely 

 decompose them. The consequence of this was that after a series of 

 experiments I found myself unable to devise a method by which the 

 combustion could be accurately carried out, and at the same time with 

 sufficient rapidity to enable the work to be completed in the time at 

 my disposal. I regret exceedingly that this should have been the case, 

 as the results of complete determination of the sulphur, both in the 

 urine and faeces, would have been most interesting. 



Ash. — In the process of incinerating the faeces for the estimation of 

 the phosphates, the ash was always roughly estimated, and so regu- 

 larly did the phosphates vary with the amount of ash, that as soon as 

 this was known I was able to make a very fair estimate of the quantity 

 present. 



When I began these researches I had the intention of determining 

 accurately the composition of each day's faeces, but it soon became 

 obvious that the results could be of but little value, and might 

 possibly be very misleading, from the extreme difficulty of deciding 

 how far those passed on a given day belong to the day before, or 

 contain something which should be credited to an earlier day, or even 

 to the very day on which they were passed. I have attempted by 



