Monthly Microscopicall 
Journal, Feb. 1, 1869. J 
Hoyal Microscopical Society. 
101 
agents I found that the same results could be brought about quite 
independently of atmospheric conditions, by immersing the sec- 
tion for about ten minutes in absolute alcohol diluted with eight 
per cent, of water, then placing it upon the glass slide, and before 
it became dry pouring over it two or three drops of acetone,* in 
which it was allowed to remain from y — 1", then tilting this off, 
and replacing by chloroform. The effects were then watched, as 
before, under the microscope, and, at the suitable time, the solution 
of Canada balsam was added and the coyering-glass applied. There 
were two great disadvantages in connection with specimens pre- 
pared in both these ways ; one was that the section itseff was more 
or less obscured by minute granules of balsam, which had been pre- 
cipitated out of its solution in a molecular condition by contact 
with the specimen ; and the other, that sections so prepared did not 
retain their characteristic appearances more than about six weeks 
or two months, — after that time they began to grow unfformly trans- 
parent, and were no longer of any use. The first disadvantage I have 
succeeded in obviating by using the solution of Canada balsam in ben- 
zole, instead of the balsam in chloroform, which fortunately gives a 
preparation similar in all other respects, but free from the defacing 
granules of molecularly precipitated balsam. The last disadvantage, 
however, in spite of all my attempts, still remains, the specimens so 
prepared have only a temporary value and will fade after from six 
weeks to two months. If absolute alcohol cannot be procured so 
as to enable the dilution I have mentioned to be made, then 
strong spirits of wine may be used instead, and the specimen 
requires to remain in the acetone for from 1"— 2" instead of for the 
shorter time before specified. I have also succeeded in making 
good preparations with ordinary spirits of wine, by immersing the 
section taken from this in acetone for about half-a-minute, then 
washing with benzole for the same time, before pouring on the 
chloroform and subsequently adding the solution of Canada balsam 
in benzole. The specimens when immersed in chloroform and found 
by microscopic examination to be fit for mounting, always present 
a slightly cloudy or opaque appearance to the naked eye, an^ this 
is generally notably increased on the addition of the solution of 
balsam in benzole. But the operator must acquire a certain 
amount of experience for himself before he will be able to use this 
method with success, and unless his reagents be all perfectly pure 
and fresh he will almost surely fail to secure satisfactory results. 
tissue that would give up their water. But the quantity remaining must be neither 
too much nor too little — if too much, the specimen becomes more or less opaque 
generally ; and if too little, as after immersion in absolute alcohol instead of spirits 
of wine, it becomes, when prepared in the same way, uniformly transparent. A 
section properly prepared should present a whitish cloudy opacity to the naked 
eye. 
* Pyroacetic spirit. 
VOL. I. I 
