used for Agricultural Purposes. 
415 
tations which occur here and there on Staffelite. No. 3 expresses 
the composition of a white botryoidal specimen from Staffel. 
In the next place, I shall quote several complete analyses 
which I made of cargo-samples of rich Nassau phosphate. 
Detailed Composition of Three Samples of German Phosphates. 
No. 
1. . 
No. 2. 
No. 3. 
1 
•78 
2-74 
2-91 
30-91 
30 - 24 
44 
22 
43-81 
41-58 
42 
7 
38 
6-66 
8-86 
1 
65 
2-18 
1-89 
5 
34 
S-45 
3-90 
3 
48 
5-25 
10-62 
100 
00 
10-000 
100-00 
77 
99 
67-48 
66-01 
3 
75 
4-95 
4-22 
It will be seen that these three samples contained a consider- 
able amount of oxide of iron, and only a moderate percentage 
of carbonate of lime. Notwithstanding the high percentage of 
phosphate of lime in No. 1, this sample contained rather more 
than 7 per cent, of oxide of iron, and had a reddish-brown 
colour as deep as that of the two other samples. 
There was nothing in the appearance of No. 1 indicating its 
superior character in coipparison with No. 2 and No. 3 samples. 
On the contrary, any person judging it by its brown colour might 
have been excused for taking it to be low-quality phosphate. 
Colour, then, cannot be relied upon in forming a correct esti- 
mate of the quality of Lahn phosphate. It is true the highest 
quality samples are generally white or light yellow, but at the 
same time I have met repeatedly with nearly white samples, 
which, on analysis, did not turn out to be particularly rich in 
phosphoric acid ; and No. 1 is an example of a decidedly brown- 
coloured mineral phosphate, which was found to be unusually 
rich in phosphate of lime. Generally speaking, the appearance 
of most phosphatic minerals affords but little insight into their 
true character ; and this remark holds good, specially in the 
case of German phosphates, which vary more than, perhaps, 
any other class of phosphatic minerals. Physical properties do 
not sufficiently distinguish high-class from low descriptions of 
Nassau phosphates, and chemical analysis alone reveals their 
real value. 
