164 
SUMMARY OF CURRENT RESEARCHES, ETC. 
the thickness of the sections. For instance, sections cut with five teeth 
of the rocking microtome require generally about an hour to dry in the 
way I have described ; those cut with ten teeth perhaps three hours ; 
while those cut with fifteen teeth take six hours, or even longer. This 
scale is only approximate, and it may be said, generally speaking, that 
the longer the slide is allowed to dry the better will be the fixation, and, 
of course, no harm is done to the section by leaving it for an indefinite 
time in paraffin, so long as the paraffin is not melted. 
Of course a single section is to be mounted in the same way as a 
series, and it w T ill be found that where it is desirable to examine a few 
sections with as little delay as possible, warm methylated spirit, or even 
absolute alcohol, evaporate more rapidly than water, while the fixation 
is as perfect with them, and the method of use exactly the same, as with 
the less volatile liquid. For obvious reasons these fluids are not likely 
to be used frequently with long series of sections.” 
(6) Miscellaneous. 
Detection of Adulteration in Linseed and in Linseed-oil Cake.* — 
51. J. Van den Berghe finds that linseed oil-cake is adulterated in com- 
merce by a large number of foreign substances, among the most 
frequent being colza, mustard of various kinds, hempseed, Bicinus, 
Araclris, poppy, &c. For detecting these adulterations he recommends 
treating the linseed successively with sulphuric acid (2 -5 per cent.), 
soda (2 - 5 per cent.), alcohol, and ether, and then digesting for some 
hours in the cold with a concentrated solution of calcium chloride. 
This makes both the pericarps and the testa of seeds so transparent that 
the distinctive characters of the various kinds can be readily recognized 
under the Microscope. The nutritive reserve-substances of linseed 
being chiefly aleurone-grains and drops of oil, iodine solution should 
not give the blue reaction when the oil-cako is pure. 
* Tourteaux et farines de lin (G pis. and 24 microphot.). Sec Bull. Soc. Belg. 
Micr., 1891, p. 1G0. 
