38 
NOTES AND MEMOKANDA. 
compositions Lave commenced in the fluid ; but as these progress its 
staining energy again diminishes. It has also certain disadvantages 
when used after other reagents. Thus, if applied to specimens pre- 
viously coloured by silver, the black markings are promptly dissolved 
and the preparation is rendered useless. Thiersch therefore proposed 
as a substitute a rather complicated fluid, in which the ammonia was 
nearly neutralized by oxalic acid, and decomposition prevented by the 
presence of alcohol. This fluid was advantageously employed at the 
Museum for several years, but its proper preparation requires care and 
skill, and it gives no better results than the simpler method which 
will presently be recommended. In the same work, Thiersch advised 
for certain special purposes the use of carmine dissolved in a saturated 
solution of borax ; and, with some modifications, this method is pro- 
bably the most useful of any yet proposed. According to his formula, 
one part of carmine by weight is dissolved in sixty parts of a saturated 
solution of borax, the fluid mixed with twice its volume of absolute 
alcohol, filtered, and the filtrate used for staining. These directions 
have been quite extensively copied. It will be found, however, that 
the greater part of the carmine, crystallizing in some as yet unstudied 
combination with the borax, remains on the filter, and the fluid which 
passes through is comparatively pale, and stains but slowly. On the 
other hand, the crystals which remain on the filter, if dissolved to 
saturation in distilled water, yield a fluid which stains with great 
energy and uniformity. At first it might be supposed that the same 
quantities of carmine and borax solution might be mixed, and would 
answer every purpose. So, in truth, it would, when first mixed. On 
standing, however, like the ammoniacal solution, this mixture decom- 
poses. Precipitation by absolute alcohol effects some change in its 
composition which secures its preservation unaltered for a considerable 
time. The solution made by dissolving the crystals just described in 
distilled water should therefore be employed. It should be filtered 
and transferred to a well-corked or stoppered bottle, in which it may 
be preserved several months without deteriorating, and will be found 
to be the most convenient carmine solution for staining. 
Application of the Microscope to Petrography and Mineralogy. 
—We learn from the ‘ Neues Jahrbuch fur Mineralogie,’ Ac., that Herr 
Eosenbusch observes under the microscope the action of pulverized 
minerals with reagents, such as disengagement of gas, gelatinization, 
&c., which show when these minerals consist of mixtures. The method 
of effecting various reactions which can be observed under the micro- 
scope is described. 
A New Old Book on the Microscope.— We learn from America 
that a book which was first issued nearly twenty years ago has just 
come out in a new edition. It is Professor Brocklesby’s ‘ Views of 
the Microscopic World.’ We regret to learn from some of our Ame- 
rican contemporaries, however, that it is in many respects an inferior 
book to the old one, that in point of fact it has not been brought down 
to the time. Most probably we shall soon have a copy of the work 
ourselves, and can then pass our own opinion on it. 
