1874.] Notices of Books. 10g 
iron ores. It is remarkable how generally chemists overlook the 
fact that, when a substance has been ignited to remove organic 
matter, its phosphoric acid will be to a great extent converted 
into pyrophosphoric acid. Unless special precautions are taken 
for its re-conversion, the amount of phosphoric acid found will be 
decidedly erroneous. 
The analysis of copper ores is very fully and clearly explained. 
Now methods so accurate, convenient, and rapid as the ‘‘ Mans- 
field”? and ‘‘ Luckow’s”’ are known, the question arises why the 
Cornish dry assay, which gives tolerably correct results only in 
the case of rich ores, should still be recognised ? 
Space will not permit us to examine this work at greater 
length. But although on certain points we should differ to some 
extent from the author, we can conscientiously recommend the 
work, not merely as a text-book for the student, but as 
a useful manual of reference to advanced and experienced 
chemists. 
Workshop Appliances; including Descriptions of the Gauging 
and Measuring Instruments, the Hand-Cutting Tools, Lathes, 
Drilling, Planing, and other Machine Tools used by Engi- 
neers. By C. P.*B. SuHELLey, C.E., Honorary Fellow of 
and Professor of Manufacturing Art and Machinery in 
King’s College, London. London: Longmans, Green, and 
Co. 1973: 
Turis also forms one of the series of Text-Books of Science, in 
course of publication by Messrs. Longmans, Green, and Co.; the 
subject embraced is, however, far too vast to be properly com- 
prised within the pages of a single volume. As a text-book for 
novices, it may be of some value; and that part which relates 
to the use of hand tools will be found instructive, but it is the 
only portion of it which possesses any originality. The first 
chapter, ‘“‘On Measures of Length, and Methods of Measuring,” 
is almost a reprint from another source, but it is interesting, and 
forms a good introduction to the subjects subsequently treated 
of. The description of ‘“‘ wire gauges” is defective, inasmuch 
as no mention is made of Mr. Latimer Clark’s proposed gauge, 
with which the author should be well acquainted. The latter 
half of the book, which relates to machine tools, is of but little 
use; the descriptive part is deficient, the mechanical details are 
insufficiently explained, and many of the illustrations are from 
old worn-out blocks which we recognise as having repeatedly 
seen in manufacturers’ illustrated trade circulars. This portion 
might well have formed the subject-matter for a separate volume, 
and no doubt, if more space had been available for the purpose, 
Mr. Shelley would have done it fuller justice than he has been 
able to do within the limits to which he appears to have been 
confined. 
