374 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
that he has quite failed to understand the meaning of the passages he 
has been so liberally quoting. 
Where the author adheres strictly to his own subject, viz. the 
grinding, polishing, and mounting of lenses, the work will be found 
full of tips, wrinkles, dodges, and all that kind of information which is 
so useful to an amateur. 
Dental Microscopy.* — This work, which the author states is the 
first written on the subject, is not intended to teach dental histology, 
but simply the methods of research as at present in vogue in this special 
branch of minute anatomy, and which are only cursorily treated in 
the majority of ordinary text-books. There is a preliminary chapter on 
the Microscope and its accessories, so sketchy and imperfect, however, 
that it had been better omitted altogether. One or two extracts will 
serve to justify this opinion. Mr. Smith advises the purchase of a 
substage with focusing and swinging ( sic ) adjustments and an Abbe 
condenser, but all the subsequent reference made to the latter is that it 
should be used with the 1/6 objective in conjunction with the concave 
mirror and a small diaphragm. It is little wonder, therefore, that the 
author is of opinion, “ It will be some time before the beginner can 
manipulate the substage condenser in a satisfactory manner,” and thinks 
“ it is unnecessary to add a long account of it ; experience in its use, as 
throughout microscopy, is by far the best instructor.” In recommending 
the student to use low powers only for many weeks, Mr. Smith remarks 
that with these “ the tendency towards errors of refraction of light is 
considerably lessened,” whatever this may mean, and that with high 
powers “there is greater fear of spherical and chromatic aberration.” 
This is indeed Microscopy as she is taught. When, however, we come 
to the essential and larger part of Mr. Smith’s work, viz. the preparation 
of hard and soft dental tissues, there is little to find fault with and much 
to commend ; the methods advised are those found most suitable by the 
latest investigators here and abroad, and nothing of consequence appears 
to have been omitted in the processes of decalcifying, hardening, and 
staining. The book is illustrated by eight lithograph plates, and there 
is the inevitable chapter on photomicrography. It will, no doubt, be 
of service to such as are specially concerned with the minute structure 
of the teeth. 
Lacquering of Microscope Tubes and Stands.j — Some practice is 
required in order to successfully lacquer a Microscope tube. The best 
process ig to close the ends with cork and immerse in hot water. Before 
applying new lacquer the old must be removed by means of a soap 
solution containing benzol and alcohol (1 part of olive oil soap, 3 parts 
of 94 to 95 per cent, alcohol, 3-4 parts benzol, 1 part of caustic potash). 
The tube is then thoroughly cleaned and polished and placed in the hot 
water. The lacquer, which consists of red shellac dissolved in 95 per 
cent, alcohol in the proportion of 1 : 10, is poured into a deep saucer. 
The tube is then taken out of the water, carefully dried, and the lacquer 
applied with a broad brush. 
* A. Hopewell Smith, L.R.C.P., M.E.C.S., &c., ‘ Dental Microscopy,’ London, 
8vo, 1895. 
f Central-Ztg. f. Optik n. Meclianik, xvi. (1895) pp. 55-6 
