Mr. William Phillips on the Oxyd of Tin. 361 



by that of hemitrope. The seeming confusion produced by the 

 made,* is very often much augmented by circumstances apparently 

 resulting from no law, by which parts of crystals are jumbled to- 

 gether, so as to form a whole, that can Only be understood by a 

 long and patient investigation, which in the end serves only to 

 satisfy the observer of the absence of all regularity in the disposition 

 of the several constituent parts, although each may be separately 

 defined. 



But even the regular macles of the oxyd of tin seem, at first 

 sight, to form no very intelligible part of the series of its crystalli- 

 sation, although they are in fact very interesting. To understand 

 them it needs only to become well acquainted with some of the most 

 simple; as, for instance, with those of ngs. 186, 187, 188, and 

 189, PI. 24, which will serve as a ready clue to the comprehending 

 of all such as are of regular formation ; and by these it will be seen 

 that they all proceed from the same law of section. 



The made first described by De Lille, who ascribes to Lhermina 

 the developement of the law by which it takes place, is that of fig. 

 186, and will be understood by referring to fig. 190, on which the 

 dotted lines a b c d e represent a section of it, parallel with the 

 edges ef of the upper and^ h of the lower pyramid f dividing the 

 crystal into two parts. The upper part is represented in the same 



* I have retained the term made in preference to that of licmitrope, because the 

 latter does not in fact apply to any one of them. It does not seem to me that the term 

 made is objectionable, because it has been given to a substance. In this case it only 

 denotes a czVcMOTJ^««rc, and no one would think of asking for macles, without adding, 

 of tin, of the ruby, &c. 



+ The section by which this, as well as the succeeding macles, takes place, being 

 parallel with the edge of the secondary pyramid, it follows of course, as a reference to 

 the series of the second modification will shew, that this section must also be parallel 

 with the faces of the primitive octohcdron. 



