210 THE YEAR-BOOK OF AGRICULTURE. 



Report on the Gases Evolved in Steeping Flax, and on the Composition of 

 the Dressed Flax Fibre. 



BY JOHN F. HODGES, M.D., F.C.S., Prof, of Agriculture, &c. Queen's College, Belfast. 



THIS report contains the results of investigations which were undertaken in connection 

 with the technical processes employed in the preparation of the flax-plant for textile pur- 

 poses. The attention of the author was chiefly directed to the examination of the method of 

 steeping in water heated by steam, introduced by Schenck, and usually termed the hot-water 

 system. In this process, which was fully described in a report made to the British Associa- 

 tion for the Advancement of Science, at the Belfast meeting, it was found that the chemical 

 changes produced by the fermentation of the flax straw in water maintained at a temperature 

 of 90 F., did not materially differ from those which accompany the ordinary method of 

 steeping in pools in the open air; and that, in fact, Schenck' s method might be regarded as 

 merely the common process of the Irish farmer, accelerated and subjected to scientific control ; 

 the peculiar fermentation by which the adhesive matters of the straw are softened and dis- 

 solved being attended in both cases by the production of a considerable amount of butyric 

 acid. 



Examinations of the gaseous products of the fermentation were made at steeping-works in 

 the neighborhood of Belfast, and also in experimental works in Queen's College; the water 

 contained in the experimental vats being maintained at the requisite temperature by pipes 

 conveying steam from the boiler of an engine connected with the college heating apparatus. 

 The gases evolved from the fermenting liquid were analyzed in accordance with the processes 

 proposed by Bunsen, and were found to consist of carbonic acid, hydrogen, and nitrogen. 

 No traces of carbonic oxide, carburetted hydrogen, nor of sulphuretted hydrogen were 

 detected. The following was the corrected composition of the mixture of gases collected in a 

 trial of Schenck' s process, in the steeping- vats in Queen's College. The carbonic acid was 

 removed by the introduction of balls of caustic potash, and the residue examined by explosion 

 with oxygen, &c. 



Composition in 100 vols. 



Carbonic acid 22-29 



Hydrogen 44-30 



Nitrogen 33'41 



Composition of dressed flax. It was usually assumed, formerly, that by the process 

 employed in the preparation of flax for spinning purposes, the fibre was deprived of all the 

 constituents which the plant, during its growth, had extracted from the soil, and that it 

 might be regarded as possessing the same composition as the cellulose of the chemist. This 

 opinion was, several years ago, proved to be erroneous; and the results of the following 

 analyses of samples of flax fibre show that not merely does the dressed flax of commerce con- 

 tain a portion of the inorganic matters of the plant, but that there remains locked up in the 

 cells of the fibre a considerable amount of the nitrogenized and other proximate compounds of the 

 unsteeped straw. The following were the methods adopted in the examination of the flax 

 fibre: The fibre, cut into small pieces, was repeatedly treated with cold water so long as 

 any thing dissolved. The solution obtained was strained through linen, and afterwards 

 filtered. On boiling the filtered liquid, only a slight troubling was observed ; but on the 

 addition of a few drops of acetic acid, a precipitate of caseine was obtained, which, after 

 twelve hours subsidence, was collected, washed, dried, and weighed. In the liquid from 

 which the caseine was separated, when evaporated almost to a syrupy consistence, alcohol 

 produced a bulky grayish precipitate, which was collected, washed, and dried. The alcoholic 

 liquids, on concentration, afforded a rich orange solution, and gave, on evaporation, a reddish 

 brown residue, which when heated, evolved a strong caramel-like odor, and its solution had 

 a sweetish taste, and afforded the usual reactions of grape-sugar. The several precipitates, 

 after being weighed, were carefully incinerated, and the weight of ash obtained in each case 

 deducted. The determinations of the amount of nitrogen in the samples were made accord- 

 ing to the method of Will, and included first, the estimation of the total amount of nitrogen 

 in the dried flax, and secondly, of the amount which was retained in the form of insoluble 



