Be ed wi S 
on) ra al ita aces rane ST Ey a oes ee 
1876.] Microscopy. 563 
MICROSCOPY.! 
Recoeyition or Woor in Mixep Fasrics. — Any child at all fa- 
miliar with the instrument can instantly distinguish wool from cotton, 
linen, and silk, as figured in the common books on the microscope ; but 
the exigencies of modern commerce have developed new and difficult 
questions in regard to the diagnosis of wool. The Treasury Depart- 
ment of the United States, after having from June, 1870, down to Feb- 
tuary, 1875, admitted certain fabrics, known as “calf-hair goods,” free 
ftom those duties which would be levied upon goods composed in part of 
woolen fibres, on certificate from the manufacturers of such articles that 
they were made entirely of cow-hair, calf-hair, and vegetable fibres, and 
contained no wool or worsted in any form, became possessed of strong 
evidence that these fabrics were not made, and could not be made, wholly 
Without wool, and submitted the question to the National Academy of 
Sciences for investigation, furnishing more than ninety samples of these 
goods as materials for study. Drs. J. J. Woodward and J. L. Leconte 
Were appointed a commission to investigate the subject, and at their re- 
quest Drs. J. G. Hunt and E. M. Schaeffer made a careful microscop- 
ical examination of the samples furnished, and also, for comparison, of dif- 
ferent varieties of commercial wool and of hair from different animals, 
and prepared mounted samples of each for further study and comparison. 
e fibres, having been rendered opaque by the dyestuffs previously em- 
ployed, were bleached in dilute mineral acids, mounted in glycerine, and 
examined mostly with powers of from } to 4 inch, except for estimating 
percentages, for which lower powers were employed. In a few of the 
‘amples submitted no wool was found, or only doubtful hairs, or a few 
fibres, not certainly indicating an intentional admixture. In a larger 
Proportion of cases there was not much wool, while in a very large num- 
ber of Samples there was from five and ten per cent. to a much larger 
Proportion ; in one case it being difficult to find five per cent. of genu- 
ine cow-hair. 
As a result of these observations, and of a subsequent verification of 
m, the commission submitted to the Secretary of the Treasury a re- 
Port which contributes largely to the clearness of our knowledge of the 
relations of wool to other kinds of hair, and which is published, with ex- 
cellent heliotype illustrations, in the Bulletin of the National Associa- 
n of Wool Manufacturers, December, 1875. 
x While it is remembered that some microscopists deny the possibility of 
distinguishing the hair of the cow and calf from that of the sheep, and 
others differ among themselves as to the result of observations on 
© same Samples, and while it is admitted that both kinds of hair are of 
*Yery similar structure in respect to the arrangement and details of their 
Medullary, cortical, and cuticular portions, it is still confidently asserted 
1 Conducted by Dr. R. H. Warp, Troy, N. Y. 
