On a Difficulty in Isomorphism. 53 



shall determine one coincidence more to accord with the 

 doubled atoms of sodium and silver ; then, for aught I can 

 see, the doctrine of oxygen-salts having oxides for their 

 bases must at once be abandoned ; but, if observation shall 

 determine any coincidence to accord with the received atoms 

 of sodium and silver ; then, if we admit coincidence in form, 

 we must also admit discrepancy of constitution, for though 

 barium substitute these metals in compounds, without affect- ' 

 ing the form, it must be in the proportion, hoth of atom for 

 atom, and of one atom for two atoms; then, too, must we 

 seek for an explanation of all known coincidences, however 

 striking in form and in constitution, in the emptiness of 

 some such phrase as *' a random-concurrence in the chance- 

 disposition of atoms;" and, then, must all the specious 

 fabric of isomorphism, stable though it seems, vanish like 

 a dream. 



Sir, I am. 

 Yours, with sincere esteem, 



Thomas Clark. 



Marischal College, 

 Aberdeen, April 1, 1836. 



Article IX. 



Examination of the water of the North Well at Scarborough, 

 By Robert D. Thomson, M. D. 



I am riot aware that any recent analysis of this water has 

 been published. A book was written on the subject, about 

 the beginning of last century ; but it is scarcely necessary 

 to say, that, the results given in that work are completely 

 at variance with those which I obtained. 



In the specimen which I examined, the water was trans- 

 parent and colourless ; a few brownish red flocks were, how- 

 ever, deposited at the bottom of the bottle in which the 

 water was contained. Its specific gravity was 1-003354. 



The presence of sulphuric and muriatic acids and of lime 

 was indicated by muriate of barytes, nitrate of silver, and 

 oxalate of ammonia ; litmus paper was not acted on. 



1. 1000 grains of the water were placed in a phial which 

 was laid in an inclined position on the sand bath until the 

 liquid was evaporated to dryness. The residue weighed 



