252 MEMOIR OF DR. DALTON, AND 



" The improvements I would propose in the use of tests 

 are, that the exact quantities of the ingredients in each 

 test should be previously ascertained and marked on the 

 label of the bottle; this might easily be done in most of 

 them in the present state of chemical science. We should 

 then drop in certain quantities of each from a dropping 

 tube graduated into grains till the required effect was pro- 

 duced; then from the quantity of the test required, the 

 quantity of saline matter in the water might be determined 

 without the trouble of collecting the precipitate; or if this 

 was done, the one method might be a check upon the other." 

 This method of testing, which promises to be of such great 

 value in saving the time of chemists, was then clearly seen 

 by him, although it has taken several workers in the field to 

 bring it into use in the laboratory, chemists, like others, 

 being difficult to move into a new train of thinking and act- 

 ing. At the same time the mere advice is not enough, it is 

 needful to show how it may be accomplished in various in- 

 stances ; this, Dalton did partially. He gave the right 

 directions as a master, leaving it for a long train of workmen 

 to carry out his ideas. Still we see clearly that he was accus- 

 tomed to use the graduated dropping tube, and analyze by 

 volume. He gives directions for taking the alkalinity of 

 water by the use of acids, and adds, that " these acids may 

 be considered as sufficient for tests of the quantity of lime 

 in such waters, and nothing more is required than to mark 

 the quantity of acid necessary to neutralize the lime." Here 

 we see that he was accustomed to take the alkalinity of waters 

 for the carbonate of lime. 



There is certainly a change in the style of these memoirs, 

 there is less care, there are opinions thrown out and un- 

 finished experiments which do not directly lead to benefit, 

 and there is a diminished desire to give the ultimate laws on 

 which phenomena depend. The mind had evidently felt that 

 something bad been achieved, which left it leisure and gave 



