63 
insoluble siliceous matter; the woody structure was distinctly preserved, 
its organic matter having been replaced mainly by phosphate of lime. 
At Cwmgynen, in North Wales, phosphatic minerals have been dis- 
covered near the lead-bearing clay-slate districts of Llangynag, in the 
Liandeilo series of Silurian rocks. A specimen taken from a compact 
block weighing one cwt. showed 64.77 per cent. of tribasic phosphate, 
with 22.14 per cent. of insoluble siliceous matter. This, however, was 
remarkable; the per cent. of phosphate in four other specimens ranging 
from 50,08 to 58.68. Two other cargo-samples showed 40.75 per cent. 
and 28.68 per cent. The two last named are hardly worth transport- 
ing any distance. North Wales has an abundance of phosphatic shale, 
but not of a character very available for market. 
Canadian phosphates show a high percentage, good cargoes averag- 
ing from 70 to 72 per cent., and cargoes of less than 65 per cent. are 
rarely shipped. The per centum of siliceous matter is very low, five 
analyses varying from less than 1 per cent. to 13.50 per cent. They are 
difficult, however, to pulverize, but are of easy manipulation in the 
manufacture of concentrated superphosphate. The transportation 
across the ocean is a heavy tax on this production. 
Spanish and Portuguese phosphorites of a white or yellowish color, 
vary in hardness and in the proportion of phosphate. In Spain, they 
are often found in solid beds, alternating with limestone and quartz. 
The latter is frequently mixed largely with the phosphorites, but the 
former in small quantity. They belong to the class of fluoride apatites, 
the fluorine often amounting to 14 per cent. Four rich specimens 
showed from 76.17 to 86.14 per cent. of phosphate of lime. ‘Phe insolu- 
ble siliceous matter varied from 2.75 to 15.41 per cent. The highest 
per cent. of phosphate found by Dr. Voelcker was nearly 89, but car- 
goes in England seldom yield over 72, and the majority from 60 to 65. 
Twelve recent cargo-samples ranged from 56.19 to 75.25; in soluble 
siliceots matter from 4.98 to 37.29. The better qualities ground 
fine and treated with sulphuric acid produce light-colored concen- 
trated superphosphates. They find ready sale and higher prices 
for their phosphate than coprolites and mineral phosphates contain- 
ing much oxide of iron or alumina. They retain their high propor- 
tion of soluble phosphate unaltered by keeping, whereas those made 
from materials strongly impregnated with oxide of iron and alumina are 
apt to precipitate a portion of this valuable element, and to reduce 
another portion to the insoluble state. 
Extensive workings of mineral phosphate are formed in the Lahn 
Valley, in the duchy of Nassau. The mineral occurs in pockets imbed- 
ded in ferruginous clay, but in some places it forms compact masses of 
earthy fracture, and of a light-gray or yellow color. Again it appears 
as a conglomerate of broken pieces cemented with red or brown clay, 
and mixed with greenstone, manganese, and iron. Rarely it occurs in 
slates of shaly fracture or in crystalline masses. Its richest varieties 
are botryoidal in structure and nearly white or yellow. The latter are 
becoming scarce, and the exportation to England has been almost ar- 
rested by the depreciated quality of the product. Three rich specimens 
from Staffel showed from 79.01 to 88.54 per cent. of phosphate, with but 
slight proportions of siliceous matter. Three cargo-samples gave from 
66.01 to 77.99 of phosphate, with insoluble siliceous matter ranging from 
3.48 to 10.62. Color and other external characters are a very imperfect 
test of the excellence of these minerals, which is made apparent only 
by chemical analysis. The foregoing, however, are above the average 
value of German or Nassau phosphates. Six cargo-samples are noted, 
