82 Dr. Kane on the Compounds of Ammonia. 



supposed ; in the first class, the substituting equivalents being oxides of the same, 

 in the second they being oxides of different bases. Thus in the former, two atoms 

 of lime, magnesia, or of water ; in the latter, one of lime and one of water, or 

 one of magnesia and one of water, likewise lime and magnesia without water, 

 lime and protoxide of iron, &c. The complication thus arising must render new 

 researches for the determination of the point not only necessary, but very diffi- 

 cult ; and hence, although I would look very sanguinely to a re-examination of 

 the harmatome and zeolitic groups for a great accession to our accurate know- 

 ledge of this department of science, I have not been able to deduce from analyses 

 at present recorded any definite results, except in one instance, which, however, 

 in itself may be almost looked upon as conclusive. 



This example consists in the group of minerals consisting of natrolite, meso- 

 lite, and scolezite, which constitute one of the best instances of isomorphism 

 that has been as yet found, and are related to each other in constitution in a 

 very simple manner : the natrolite being a hydrated silicate of soda and alumina, 

 the scolezite being a hydrated silicate of lime and alumina, and the mesolite, 

 probably a product of the crystallizing of the two together, being intermediate 

 in constitution. Now the formula accurately given by analyses for the pure 

 species are, thus, 



Nao . s^03 -\- A^Og . sz'Og -j- 2 ho 



and 



cao . s^03 + a/jOj . si'Oj -|- 3 ho, or better, 



cao . HO . sioj -\- aI^o^ . siog -\- 2 ho. 



Here the equivalency of cao. ho to noo is most remarkable, and certainly must 

 be allowed to go a great way towards confirming the views regarding the nature 

 of the compounds of ammonia, from which the analogy of nh.j.h to H.o, and 

 hence to coo or ugo, and of nh^o to cao . ho, &c. was first arrived at.* 



* Since the above views were completely formed, and the memoir read, I was singularly struck 

 by finding in the Elemente der Crystallographie of Gustav Rose, the same view suggested of the 

 replacement of soda, not by lime, but by its hydrate. Intending to commence an examination of 

 the zeolitic group under the point of view noticed above, I began by the study of their crystallogra- 

 phie relations, to which I had not before applied myself, and selected his work as the system best 

 adapted to my purpose. In speaking of the composition of wernerite, (page 158,) the following pas- 

 sage occurs, which, as the work is not very common in Ireland, I shall translate. " The above 



