1864. | Elementary Chemistry. 561 
merous, that if is most difficult even for the fully initiated to clearly 
define them, so as to make them clear to a bystander. Hence there is 
little wonder that a non-professional artist who knows not what he is 
to see, should be puzzled tomake them out, and still more so to depict 
them. Of this, every writer, Mr. Hogg amongst the number, com- 
plains, and all find it most difficult and costly, sometimes almost im- 
possible, to obtain truthful representations of those numerous changes 
in the eye, which the pathologist is so anxious to secure. Should 
hereafter photography be capable, as we now incline to hope it may be 
(it has already been most usefully applied in depicting accurately and 
cheaply external changes and diseases), at no very distant time, of illus- 
trating the hitherto hidden recesses of the human eye, it will supply a 
desideratum of no ordinary importance ; for an absolutely correct pic- 
ture of the living eye in health and disease will then be within the 
easy reach of every student of medicine, and thus one great cause of 
ignorance will be removed. While, therefore, Dr. Roseburgh cannot 
as yet lay claim to complete success, he deserves credit for the advance 
which he has made on the road to it, 
ELEMENTARY CHEMISTRY.* 
Dr. Arsoun, Professor of Chemistry in the University of Dublin, has 
recently added another to an already numerous class, the Manuals of 
Chemistry for beginners. It is said that few preachers close their 
useful careers without, at some time or other, publishing a sermon or 
volume of sermons. A like result appears to occur under similar 
circumstances with another class of men. Most of those who have 
to deliver at stated intervals a course of elementary scientific lectures, 
in which, owing to the quickly-changing audience, there is not scope 
for much extension or variety, feel tempted to commit to print their 
favourite explanations and demonstrations, and not a few yield to the 
temptation. 
As might be expected, the little books developed under these con- 
ditions bear a strong resemblance one to another. Dr. Apjohn’s 
manual is a fair specimen of this class, not among the worst, but, we 
must in honesty add, not among the best. 
We preter, therefore, to offer a few general remarks upon elementary 
works in chemistry, using that of Dr. Apjohn by way of illustration, 
rather than to attempt a detailed criticism of a not very characteristic 
performance. In one respect, however, Dr. Apjohn has departed from 
the established usage ; we mean, in the limitation of his subject-matter. 
He leaves the vast topic of organic chemistry untouched, excepting 
that he gives a brief account of a few of the simplest and most com- 
monly occurring combinations of carbon, such as oxalic acid and 
= ¢Manual of the Metalloids.. By James Apjohn, M.D., F.R.S., M.R.LA., 
Professor of Chemistry in the University of Dublin. (One of Galbraith and 
Haughton’s ‘ Scientific Manuals.”) Longmans. 
