CLARKE AND"] 
BTEIGEB. J 
CONSTITUTION OF PYKOPHYLLITK AND CALAMINE. 
17 
By heating with dry ammonium chloride, pyrophyllite is very slightly 
attacked. In two experiments it lost in weight G.17 and 6.30 per 
cent, respectively. The excess of loss over water is due, as we have 
proved, to the volatilization of a little ferric and alnminic chloride. 
The residue of the mineral after this treatment contained no chlorine, 
so that no chlorhydrin-like body had been formed. The formation of 
such a compound, the replacement of hydroxyl by chlorine, would, if it 
could be effected, be a valuable datum toward determining the actual 
constitution of the species. 
Calamine. 
The simplest constitutional formula for calamine, the one which is 
generally accepted, represents it as a basic metasilicate, Si0 3 =(ZnOH) > 
In this the hydrogen is all combined in one way, and so, too, is the 
zinc. In ail other possible formulae, simple or complex, the hydrogen 
as well as the zinc must be represented as present in at least two 
modes of combination: a condition of which, if it exists, some evidence 
should be attainable. Our experiments upon calamine have had this 
point in view; and we have sought to ascertain whether water or zinc 
could be split off in separately recognizable fractions. Our results, in 
the main, have been negative, and tend toward the support of the 
usual formula: but the data are not conclusive, although they seem to 
be worthy of record. 
The beautiful white calamine from Franklin Furnace, Xew Jersey, was 
selected for study, and gave the subjoined composition: 
A a aly 818. 
Fractional water 
At 100= 27 
At 180- 22 
At 250- 75 
At300 c 88 
Incipient red heat 1. 46 
Full red heat 1. 37 
Bull. 167- 
7.95 
