OF THE SEVEN WELLS, 



115 



recorded their results in this way,—" inter alios," Doctor 

 Parkes, 



Column G. has been inserted. 1st, because many experi- 

 menters have chosen this mode of expression, and secondly, 

 because the results thus shown will probably be more 

 readily appreciated by those who are not professed Chemists, 



^HF It being remembered that, in the 16th of a Gallon, 

 2*56 grains of organic matters are present, therefore 40*96 

 grains will be present in one Imperial Gallon. 



A few remarks on the Table just given seem to be called 

 for, in order to point attention, in the first instance, to the 

 differences in the materials employed, Nos. 1, 2, 3 and 7 

 are materials to which no other than mechanical action has 

 ever been attributed. By this agency, they separated from 

 one-sixteenth of a gallon of the same water respectively,— 



Grains, 



1 Ordinary paper *23 



3 Clean white sand, ... *51 

 7 Finely divided mica ... *73 



2 Swedish filter paper ... -.93 



These figures, if the original amount of organic matter pre- 

 sent in one-sixteenth of a gallon be taken as 100, give the per 

 centage proportions shown in Column F. Thus it appears that 

 of these four mechanical agencies, No. 2 is by far the best ; 

 No. 7 the next best, and so on ; and that out of 100 parts, 

 the best mechanical means tried was only able to separate 

 36*36 parts. Nos. 5 and 6 are materials to which special 

 purifying powers have been attributed. The percentage 

 quantities separable by their means are shewn in the same 

 column of the Table to be 34*00 nearly, and 36*00 nearly; 

 i. e.j these special agencies are neither of them quite so 



powerful as the best mechanical means. Finally, the 



15 



