622 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
[February 3, 1872. 
not always, tlie illuminating pencil should fall as 
vertically as possible upon the object. Any varia¬ 
tion from this will involve certain errors which must 
be eliminated by comparison of appearances, pro¬ 
duced by varying the angle at which the pencil is 
incident. It is, of course, apparent that the safest 
plan is to vary the angle under any circumstance, 
and to view every object under as many conditions 
as possible. The merely superficial view of an 
object, which alone is possible by the use of re¬ 
flected light under such simple conditions as I have 
now considered, is of so little value in giving any¬ 
thing approaching a knowledge of the nature of 
an object under observation that every student 
will desire to prosecute his researches considerably 
further, and to investigate the texture or struc¬ 
ture. For this some preparation of the object is 
necessary. 
Preparation of subjects. —By this I do not neces¬ 
sarily mean “ mounting ” as understood by micro- 
scopists. Preparation is one stage, an early one, of 
which mounting is a later stage, but not a necessary 
consequent. Immersion of the subject in some fluid 
of different refractive powers from itself is the 
simplest mode of preparation, and often the only 
necessary one. This is the case with manj'- vege¬ 
table structures which are so transparent and thin 
as only to require immersion in water to fit them for 
examination. If the student wish to examine the 
petal of a flower, such as that of the pimpernel, his 
simplest plan is to take a glass slip, place the petal 
upon it, add a drop of water, and place upon it a 
cover of thin glass; in a very short time he will 
be able to make out the structure of the petal 
with tolerable facility and accuracy. Many struc¬ 
tures require a fluid of a higher refractive power 
than water. Such of these as come within the 
scope of the pharmaceutical microscopist I shall 
treat more in detail presently. The major portion 
of the substances examined microscopically require 
some preliminary treatment of a chemical or a 
mechanical nature. We will regard these sepa¬ 
rately. 
Chemical. —The value of reagents in microscopy 
does not seem to be so generally known to amateur 
microscopists as it should be. A somewhat long ex¬ 
perience of them leads me to assert that little can be 
learned without their use. They are not numerous: 
acetic acid (fort, and dil.), sulphuric acid (dil. 1-4), 
nitric acid (1-4 dil.), iodo-ioduret of potassium in 
solution (1 gr. iodine, 3 grs. iodide of potassium, 
1 oz. water), strong syrup, ether, nitrate of barytes 
in saturated solution, nitrate of silver (2 per cent, 
sol.), and oxalate of ammonia are those chiefly use¬ 
ful, and will be separately mentioned under the head 
of the purposes to which they are applicable. These 
reagents should be kept in small bottles, to which 
are adapted as stoppers the capillary tubes with 
india-rubber tied over the top, now so commonly 
sold as “ dropping tubes.” By the aid of these tubes 
an exceedingly minute drop may be applied to any 
desired portion of an object under observation, and 
the exclusion of foreign matter easily secured. It is 
hardly necessary to add that all chemicals used 
must be pure. Boiling, a mechanico-chemical opera¬ 
tion, is often of great service in promoting the isola¬ 
tion of portions of a structure, but should not be had 
recourse to if less violent means will answer the end. : 
Simple maceration in cold or warm water will be 
found of great sendee in the study of vegetable 
structure. The same may be said of maceration in 
syrup, glycerine, and dilute acids or alkalies, with 
, respect to mineral and animal substances. 
Mechanical. —Downright dissection when animal 
or vegetable structures are dealt with is generally 
, the most useful, certainly the most instructive. Small 
scissors, scalpels, and sewing-needles fixed in handles 
are the tools generally used. For making sections 
a razor is best. The object, if small and soft, may 
generally be best held between the linger and thumb; 
if hard, held against a piece of glass, or fixed in a 
proper section cutter. This last instrument consists 
of a tube having a movable bottom. This bottom 
is attached to a screw with a fine thread. A milled 
head outside can be revolved between the finger and 
thumb, and the whole is usually so arranged that 
one revolution of the milled head raises the bottom 
of the tube, and also the object placed in the tube, 
through ^yth of an inch. Any less distance is, of 
course, easily got at by dividing the milled head 
into 10 or 20 proportional parts. With a little prac¬ 
tice the student' will be able easily to dispense with 
this somewhat costly apparatus, at all events for 
his ordinary laboratory work. Compression and 
“teasing” are of occasional service, but patient dis¬ 
section is by far the best, and should be always fol¬ 
lowed when possible. 
It is perhaps not worth while to extend these 
papers by giving long explanations of the mysteries 
of mounting. The art of mounting, apart from that 
of preparing the objects, may be summed up very 
briefly. It consists in fastening down the thin 
covers, so that they shall not be displaced by acci¬ 
dent, or suffer the contained fluids to escape. When 
Canada balsam, Mr. White’s dammar medium, and 
glycerine jelly are used, the object “prepared ” is also 
mounted, and may be placed in a cabinet. When 
fluids are used, the edge of the cover must be luted 
down; for which purpose nothing is better than Mr. 
White’s dammar, Bell’s cement, or Bates’s photo¬ 
graphic varnish. All fluid having been removed 
from the edges of the cover, a thin coat of varnish 
is to be laid on and allowed to dry. A second, third, 
and fourth coat will finish the job, and make all 
secure. Those who require further information on 
this subject will probably go to the numerous and 
excellent text-books now before the public, and the 
subject is hardly one that can be discussed at length 
in these pages. 
I now come to the more immediate subject of these 
papers, the using of the microscope in pharmacy. 
One of the great uses of the microscope in pharmacy 
is that of a detective to discover adulterations. But 
its great use is that of an educational agent, in that 
it enables the pharmacist to become familiar with 
the nature and structure of many of the substances 
with which he deals. To a certain extent these are 
related. The microscope can only be used as a 
detective by those who have already .been educated 
by it into a knowledge of the nature and structure 
of the genuine substances they wish to distinguish 
from the spurious intermixed with them. For the 
present I do not propose to treat of the microscope 
as an educator, pure and simple. I shall deal with 
it as a detective, and as teaching pharmacists to be¬ 
come detectives also. How to detect adulterations 
by means of the microscope is then my subject hence¬ 
forward, to the end of these articles. 
(.To be continued.) 
