AS at et Ean fe ja 2 ha 
pil a shes = 
T. S. Hunt on Ophiolites. 223 
Silica, , - ; ; - : - 4510 
Magnesia, (by difference), - : - - 5468 
Protoxyd of iron, — - ;. . : F ae 
Alumina, - - : . 2 ‘ . ‘80 
Water, : . A : : ‘ - 1880 
100°00 
This residue when ignited, yielded but a trace of magnesia to 
a boiling solution of nitrate of ammonia, showing that it retained 
no carbonate; but from the excess of silica it was evident that 
4 partial decomposition of the serpentine had been effected by 
@nitric acid. In confirmation of this, I found that a second 
sats of the pulverized rock, when submitted to a prolonged 
gestion with acetic acid, left 75°5 per cent of matter dried at 
212° F.; this residue gave a feeble effervescence with nitric acid, 
which by prolonged digestion, took up 18:0 per cent of magne- 
Sia, although when previously ignited, to a 
Solution of nitrate of ammonia only a trace of lime, and but 0°3 
per cent of magnesia, Its analysis by fusion with carbonate of 
ave :— 
Silica, ; : z _ : ‘ - 48:10 
Magnesia, : ; he oe pic ee ee 
Protoxyd of iron, - - - . : < wae 
Water, - F Se : : : 11:90 
99°34 
Another specimen of the conglomerate was now pulverized, 
and eight grams of it were digested for a Jong time with boil- 
8 acetic acid: the insoluble residue, after Jevigation, was sub- 
st & second time to the same treatment. The matters thus 
ved for 100 parts of the mineral, were :— 
Carbonate of lime, - ; y : - 986 
“© magnesia, - inocn Rule 772 
2 Siren, >'+ ‘ ‘ : : nag 
16:85 
Re residue, still containing these 3°66 per cent of carbonates, 
& by analysis with carbonate of soda, the following results :— 
Biliea, (by difference), é -~ 4898 
Magnesia, ¥ i é a at - 85°64 
Protoxyd of iron, - : :  eliched 
Lime, : . . e : . (traces.) 
Loss by ignition, — - - . . F dees 
10000 
