90 Prof. Vanuxem on the Marmolite ofMr. Nuttall. 



To the above description I have but a few observations to 

 make; 1st. That no notice is taken of the cross fracture of 

 the marmolite, which, in the fresh specimens, is important^ 

 from its identity to the precious serpentine, i. e. compact, and 

 presenting those minute scales or splinters which result from 

 small portions in part detached from the mass, exhibiting the 

 appearance of wax when broken. — 2dly. I was not able, in 

 any of the specimens in my possession, either in those from 

 Hoboken or Bare Hills, to discover natural joints in more 

 than one direction, namely, that which gives the lamellar 

 structure to it. — 3dly. With respect to the opacity of the mi- 

 neral, it is true that all those specimens are opaque in mass 

 which have been exposed for a long time to the action of the 

 atmosphere ; but these if put into water become transparent, 

 and the fresh specimens possess a considerable degree of trans- 

 lucency. 



Of the Composition of the Marmolite. — I was induced to un- 

 dertake the analysis of the Bare Hill variety, from a desire 

 of knowing the proportion of each of its constituents, the 

 quantity of silex only being given by Mr. Nuttall: and finding 

 a difference between his result and my own, I was led to ex- 

 amine that also of Hoboken, particularly as Mr. Nuttall had 

 a loss of 2^ per cent. ; he omitting to deduct from the 46 parts 

 of magnesia the 2 parts of lime which he found in it. 



I should offer my result with diffidence, if I had not assured 

 myself by repeated analysis of the exact quantity of silex, 

 water and iron, in each of them, I did not find any lime in 

 the Hoboken mineral, though I tried by one of our most de- 

 licate tests — namely, oxalate of ammonia. I made no search 

 for chrome, the discovery of atoms being of no consequence 

 in the point in question. 



The modus operandi was to calcine a portion for water ; to 

 digest another portion with nitro-muriatic acid until every 

 particle was attacked ; then to evaporate to dryness by a gen- 

 tle heat, so as not to decompose the salts of iron and mag- 

 nesia in setting the silex free ; to dissolve the salts with acidu- 

 lated water, and filter. The iron was separated from the 

 liquor by succinate of ammonia ; and (;he magnesia, as the re- 

 sidue, was obtained bj' evaporating the liquor, and then cal-< 

 cining. 



In the same maimer I also analysed the beautiful precious 

 serpentine of Newburyport (Mass.), wishing to know if in its 

 composition it accorded with the European specimens ; and 

 also to confirm my opinion of the chemical identity of the 

 marmolite and serpentine. The results of these experiments 

 are as follows : 



Silex 



