COLOURING MATTER IN COTTON.

37

it of exposure to light or on heating the liquid. The alcoholic solution of the acid

sine, gives, with acetate of baryta, a white granular precipitate, which is soluble,

though with difficulty, in boiling alcohol. With acetate of magnesia it^givesat first no precipitate; but after some time a white crystalline deposit is formed,consisting of the magnesia compound. These reactions belong to the group offatty acids of which stearic and palmitic acids are members. In order toascertain the exaCt place in the series occupied by the”acid_from cotton, it„wassubmitted to analysis, the following being the results obtained :—

sin ”

Calculation.

I.

II.

ch is

C34 • •

. . .. 204

75'55

75-27

75'45

unck

h 34 .. ..

• - - • 34

12-59

12*91

13*21

>thes

04 ■. ..

.. .. 32

n-86

11-82

u-34

Dme-

lown

270

100*00

100*00

100*00

the: by, inpro-s ofters,lved,

ngly

itate

tain,

thed ind onin anatellco-tashiled.stal-hichningrrity-tingandthe

lidi,lies,•iveswithsr aon

The formula C3 4 H 34 0 4 belongs to margaric acid, one of the products derivedfrom ordinary fats. Modern researches have rendered it almost certain thatwhat was formerly called margaric acid is in faCt a mixture of stearic andpalmitic acids. In consequence, however, of the minute quantity of the sub-stance obtained from cotton, Dr. Schunck was unable to undertake any experi-ments for the purpose of separating its constituents from one another, but wasobliged to content himself with proving the presence of one of the ordinaryproducts of the saponification of fats and oils among the bodies extracted fromcotton by alkalies. The quantity procured from American cotton was, indeed,so small that he was hardly able to purify it sufficiently for the purposes ofanalysis, and the amount of hydrogen which it was found to contain differedaccordingly rather widely from that demanded by theory ; the presence ofsome impurity or other in this specimen was also indicated by its rather lowermelting-point.

As regards this fatty acid, the question will naturally arise, whether it is tobe considered a natural constituent of the fibre, or whether it is a foreignbody introduced subsequently to the gathering of the cotton, either beforeor during the process of manufacture; but this is a question to whichit is not easy to give a satisfactory reply. Persons practically conversantwith cotton spinning say that it is impossible for the cotton to be con-taminated with any substance of a fatty nature during the process of itsconversion into yarn, provided ordinary care be taken, since it can only inconsequence of gross carelessness come into contact with the oil or fat used ingreasing the machinery. On the other hand, it is quite possible that afterthe cotton has been gathered, especially during the process of ginning, aportion of the oil of the seed may escape, diffuse itself among the fibres, andgive rise to the formation of fatty acid in consequence of the attion on it ofthe alkali. Dr. Schunck has not, however, failed in any of his experiments,whether made with East-Indian or American cotton, to obtain a small quantityof a solid crystalline fatty acid.

Colouring Matter A.

This substance is easily soluble in alcohol and is left on evaporating thesolution as a dark brown, shining, brittle, amorphous resin, which is transparentin thin layers. In boiling water it softens and melts to a pasty mass, which