Mineralogy and Geology. 121 
2 
and some crystalline rocks that I could not determine among the cargoes 
Besides, the constitution of the phosphates proves conclusively that they 
have not been hardened by fire. ave made another examination of 
the rock, without the enamelled surface and am fully convinced of the 
correctuess of my views. The following are the results: 
The phosphoric acid in this table does not include the small amount 
nintoncrae the phosphates of iron and magnesia which were estimated 
parately. ; 
Phosphoric acid, - - + + = = 4622 
Lime, - ~ < » - - - - 38°75 
Phosphate of iron, - . - eaiit wiane, SBE 
Phosphate of magnesia, A) lee hs TN 0°61 
Sulphuric acid, AGE BERLE HE Gi eek COS 
Chlorine, - - we » - - - trace 
Organic matter, salts of ammonia, and combined water, 8:95 
yetoscopic water, - - 4 + 's 2°34 
dy PPAR oF a on g sO De Seen ogs 
: 99°81 
If we take from the lime sufficient to combine with the sulphuric acid, 
we have remaining of that earth 35:95, which when combined wit 
phosphoric acid and 5°78 parts of water, give a salt of the formula 
ay, , POs. 
The sinall quantity of the phosphates of iron and magnesia in this 
Specimen is worthy of notice: It is a little remarkable, that in these 
§uanos generally, while the entire amount of phosphoric acid varies but 
slightly, there is a very wide difference in the proportions of the bases 
With whieh it is combined. ; 
The “ body of the rock” of which the above table expresses the com- 
Position, was carefully separated from the white enamel before analysis. 
Baltimore, November 11th, 1856 SEO. 
without any lustre, tough, horgy and tenacious as to texture, and with 
difficulty reduced to powden® =27 |. ° 
A proper chemical examination of this substance is therefore "porn 
i 1d that of | 
