178 THE GUANO AND OTHER PHOSPHATIC DEPOSITS 
have recently obtained a specimen, of which the following is an 
analysis, the phosphoric acid being separated by Rose’s method :— 
Water sts a A 
nie matter and combined water. i so GAD 
Phosphoric acid Sus .. 43°04 
i acid ... ee wed as - te 62 
Carbonic acid ... Ne ae te es (Traces) 
ime yd ars ... 43°45 
Magnesia =e She Su ee es eo Aape of 
erric oxid dalumina ... Au ais (Traces) 
100°13 
his (as in most other analyses that I have made of t 
same "kee both calcium and magnesium phosphates are 
present. 
re the pockets gars below the water level, on the 
other et when this was attained the material altered in 
appearance, from bein soft "yellow-brown owder (when 
remoy an and allowed to’ ravi o hard grains ofa ¢c oeolate-brown 
colour, whilst the rocks were found incrusted with a hard choco- 
ate 
completely disintegrated—so much so that on remoying the crust 
oleae a milky mixture with the water. This encrastaliol 
was ipally composed of Ecges phosphate, magnesium 
phosp ate, belive absent. It slight effe ervescence with 
acid, which apparently arose e: ately tees the white specks. Its 
fracture was cease choncoidal, it gave a yellow-brown powder, 
and was very 
The foll sathig numbers show the composition of the different 
layers from the surface downwards—the material being taken i 
Betas cent. to 16 per cent. dried out on exposure to the air. The 
gy, 2nd Field. 
Top 6 inches of guano. Loss 01 aii "243 23°51 
Calcic ie ona wd 28:67 34°24 
From 6 inches down to Loss on ignition 26°24 | 16°80 
water-level Caleic phosphate 5436 63°10 
oped phosphate to Loss on ignition 2470 23°61 
inches below W. L. —Calcie phosphate 71°85 72°53 
Incrusting stone Loss on ignition 8°25 6.31 
87°59 
phosphate Calcie phosphate 86°05 
Saat 
a I ee eae cae ie ee 
