CHEMISTRY. 207 



possesses exactly the same solvent power, but it acts more slowly. 

 The brown lyes thus obtained, neutralized by hydrochloric acid, 

 g-ive a brown gelatinous precipitate ; but the coloration of the 

 liquid still indicates the incompleteness of the precipitation. 

 Neither acid in excess nor lime of baryta will precipitate that 

 which remains of the coloring matter in solution. This soluble 

 portion varies according to the amount of alkali, and especially 

 according to the duration of the ebullition ; thus, 12 hours' ebulli- 

 tion with ammonia suffices for acids to cause no precipitate in the 

 solution. The fibre treated by boiling water loses at the end of a 

 week 16 per cent, of its weight, and 18 per cent, when pressure 

 intervenes ; the matter dissolved is acid to litmus, colors the water 

 slightl3% and possesses the singular property of browning by sim- 

 ple contact with alkali. 



Considering these first characters, it is difficult to admit the 

 presence of a resinous matter. Caustic alkalies or alkaline car- 

 bonates do not act as simple solvents, for, in boiling the fibre with 

 determinate amounts of carbonate of soda or sulphide of sodium, 

 it was found that after 8 hours' ebullition no trace of carbonic 

 acid or hj'drosulphuric acid remained. Resins do not give simi- 

 lar results; they saponify equally well with sulphides and alkaline 

 oxides. Lime does not precipitate this substance dissolved by tlie 

 alkalies ; the fibre boiled with milk of lime loses the same weight 

 as in soda, a soluble combination being formed with lime, con- 

 taining 48 parts of this oxide for 100 of the coloring matter. Clialk 

 gives the same result, although more slowl}'. The treatment by 

 chalk and lime presents this particular, — that the solutions ob- 

 tained remain colorless, and that the precipitates obtained are 

 Avhite. Analysis assigns to the substance, soluble in alkalies and 

 reprecipitated by acids, the following numbers: hydrogen, 5.0; 

 carbon, 42.8 ; oxygen, 52.2. 



The research has led to the establishment of the following facts : 

 The gummy substance which adheres to the fibres of flax is 

 nothing else than pectose. The soaking or steeping of the fibre 

 appears to have for its object the determination of the pectic fer- 

 mentation, and the pectic acid which results remains fixed on the 

 flax, either mechanically or in part, in the form of pectate of am- 

 monia. The caustic alkalies in the cold form gelatinous pectates, 

 which preserve the fibre from being completely attacked. Pectic 

 acid being weak, the alkaline carbonates have in the cold only a 

 feeble action upon the fibre. Ebullition, on the contrary, trans- 

 forms pectic acid into an energetic acid, — metapectic acid ; the 

 carbonates are then strongly attacked, and their employment be- 

 comes as efficacious as that of caustic alkalies. The carbonate of 

 soda, even in large quantity, is not a cause of the weakening of 

 the fibre, which loses more strength from the employment of 

 caustic soda, especially when the lye is concentrated. The em- 

 ployment of lime, even in the cold, weakens the fibre consider- 

 ably. But the chief cause of the destruction of the solidity of 

 the fibre is too long digestion, particularly with caustic soda. M. 

 Kolb says that, after having proved the existence of pectose in 

 the unsteeped flax, and of pectic acid in the same flax after steep- 



