﻿324 _ Transactions — Chemlstrij. 



However, I will not press tliis point further as I do not wish to rely Txpon 

 one set of experiments, or upon any particular method I have adopted in them, 

 for testing the truth of my allegation. I have therefore availed myself of the 

 first test suggested by Mr. Tichborne for determining the question finally, and 

 the results of this I will now describe. 



Blue litmus paper after being well washed in distilled water free from 

 a,mmonia till of a pale violet color, had its colour veiy distinctly changed to a 

 deep bkie on being pressed while moist upon a freshly fractured surface of 

 calcspar. The failure of Mr. Tichborne to obtain a like result with this test I 

 can only explain by supposing an omission on his part to insure a sufiiciently 

 large area of contact between the spar and the paper to render the chromatic 

 change visible. 



In regard to Mr. Tichborne's second test, I take exception to the employ- 

 ment of turmeric paper, as it only shows alkalinity in any substance in which 

 it exists to a mai'ked extent, and this is not a question of degree but one of 

 condition — alkalinity or neutrality. 



That turmeric paper cannot indicate alkalinity where this does not reach 

 to a certain degree is manifest from the refusal of the organic base analine to 

 affect it, although analine acts both upon reddened litmus and the juice of red 

 cabbage as an alkali. 



Again, I find pure strychnine, though it does not afiect tiirmeric, behaves 

 with reddened litmus just like an alkaline body, and this by the way may be 

 a character of the alkaloids generally with such tests. 



Lastly, to anticipate a little of the results of the investigation referred to, 

 hydrous tribasic phosphate of lime does not coloy.r turmeric, although we know, 

 from the manner in which it may be produced and the circumstances attendiiig 

 its formation, that it must be alkaline, which character it plainly manifests to 

 reddened litmus. 



Thus we can mix alkaline solutions of chloride of calcium and tri-basic 

 phosphate of soda, and the precipitate of phosphate of lime which falls leaves the 

 supernatant solution distinctly acid. Now, as we have no reason for svipposing 

 that the phosphoric acid in changing bases has lost any ^^ortion of its com- 

 bining or neutralizing power, we are constrained to hold that this precipitate 

 is alkaline to an extent at least equally divergent from neutrality, as is the 

 acid solution around it ; and still turmeric paper does not indicate this 

 alkalinity. 



The turmeric paper test being therefore obviously unreliable for the 

 detection of alkalinity in certain cases, I rely for the verification of the correct- 

 ness of the statement in question iipon the results of the first experiment 

 suggested by Mr. Tichborne in the communication under review. 



I have to apologise for allowing such a length of time to pass ere noticing 



I 



