1885.] Microscopy. 917 
hour. Allow it to stand and cool; decant the clear fluid, add 
fresh water, and if necessary picric acid; boil, cool and decant ; 
repeat this operation until all the carmine is dissolved. Place the 
decanted fluid in an evaporating dish, add about one grain thymol 
and stand in a warm place until the volume is reduced to 25 c.c.; 
- let the solution cool; filter; wash out the residue which should be 
on the filter with 25 c.c. water; dilute the filtrate solution with 
50 c.c. water. By this means a solution ready for use, which will 
keep indefinitely and contains capo and picric acid in good 
proportions, can be prepared with certainty. 
It gives a stronger differential coloring than Ranvier’s picric 
carmine, but overstaining must be avoided most carefully ; for 
staining sections two to five minutes are sufficient. The fluid 
stains connective tissues (fibrous) deep red, striped muscle deep 
, dull red, smooth muscle, blood and horny tissues bright yellow, 
glands reddish-yellow ; with the kidney it gives differentiation of 
the different portions of the tubules; for the central nervous sys- 
tem it seems to be of little value. If rightly used it gives a sharp 
nuclear colorin 
If the aqueous solution is evaporated to dryness the residue 
may be redissolved in alcohol, giving an alcoholic carmine dye. 
This I have not yet tested sufficiently. Apparently the alcoholic 
solution will not keep but a few months. The alcoholic solubil- 
ity of the dye offers the advantage that sections stained in the 
watery solution can be washed in alcohol directly. 
A new WATER-BATH.—The following is a description of a 
water-bath planned 
by Mr. E. A. Andrews ca 
and myself, which has 
been in use for some 
time in the serra, igh 
laboratory of 
Johns Hopkins Uni- 
versity, 
e bath proper 
consists of a closed 
MEPS 
o 
round, flat-bottomed i 
basins, eight inches Fic. 1.—Surface view of the bath ni the table. 1, 
in diameter and four vaa with lid on » 2 shelf = Moles for dishes in 
inches deep, with a ; 3, open basins, 4, rectangular basins for slides ; 
distance 
5 myn for gas sates "6, hole for regulator; 7, hole for 
of two inch- thermometer. 
