88 Dr J. H. Gladstone on some Substances 



give a blue equal in intensity to that of the compounds with 

 the fixed bases. 



Baryta, or lime-water, added in excess to a solution of co- 

 menamic acid, likewise gives a fluorescent solution. 



Mr How remarks that comenamic acid usually combines 

 with bases in two proportions ; and I have strong reason for 

 thinking that it is the more basic compounds that give the 

 appearances above noted. 



Comenamate of Iron. — Sesquioxide of iron enters into two 

 combinations with comenamic acid. The more acid one is of 

 a wine-red colour, and exhibits no dispersion ; the basic one 

 is of a bluish purple, and when sufficiently diluted becomes 

 fluorescent. Thus, if nitrate of iron in excess be added to 

 comenamic acid, and water be poured on to the deep purple 

 liquid, it will change through claret and pink, and then there 

 will appear some faint blue rays, which are not exhibited 

 when a solution of bisulphate of quinine is interposed. On 

 throwing a prismatic spectrum on to this compound, I did not 

 detect the illumination of any extra-spectral rays. 



Comenamate of Quinine. — Considering that so many salts 

 both of quinine and of comenamic acid caused the phenomenon 

 of fluorescence, it seemed not improbable that a compound of 

 the two might give it with increased effect. However, experi- 

 ment proved it otherwise. To a solution of comenamic acid 

 quinine was added, until a portion of the alkali remained un- 

 dissolved, even after standing over night. The solution thus 

 obtained showed no dispersive power ; on dilution a very faint 

 blue appeared, when viewed in the most favourable positions ; 

 but it is quite possible that this may even have arisen from 

 some minute impurity. The addition of sulphate of potash 

 did not revive the blue (at least not to any extent), but the 

 slightest addition of either sulphuric acid, or potash, alone, 

 reproduced it. 



When it is remembered that only acid salts of quinine, and 

 only basic salts of comenamic acid (as I apprehend), display 

 the blue, the absence of such an appearance in this compound 

 is less improbable a priori than would at first be imagined. 



I have added comenamic acid to solutions of several salts 



