Organic Acids on Cotton and Flax Fibres. 109 



per cent of tartaric and citric acid have but a slight action 

 on cotton and flax fibres at 80°, 100°, and 126° C, oxalic acid 

 has a decidedly injurious action, the slightest effort being suf- 

 ficient to tear the fabric. In fact, the fibres were nearly as much 

 injured as if they had been acted on by a weak mineral acid. 



In order to ascertain what quantities of citric and tartaric 

 acid were required to weaken materially cotton and flax fibres, 

 I employed solutions of these acids containing four per cent, of 

 each, and pieces of fabrics were dipped in such solutions, dried 

 in the atmosphere, and submitted to the action of heat. The 

 results are contained in Table II. 



These results left no doubt that two per cent, oxalic acid 

 acted on the fibres with still more intensity than four per cent, 

 of citric and tartaric acids ; and at the temperature of 126° C. 

 all the fabrics presented a scorched appearance, and those with 

 tartaric and citric acids had assumed a much browner tinge. 



To enable me to form an opinion whether the coloration of 

 the linen was owing to the action of the acid on the fibres, or 

 to partial decomposition of the acid itself, I took some of the 

 scorched pieces of fabric, and boiled them with distilled water. 

 The coloration not disappearing, I added a little caustic alkali, 

 but without any better results. I therefore conclude that the 

 coloration of the fabric was attributable to the action of citric 

 and tartaric acids, or to some of their derivative compounds. 



The next series was made by dipping for a few minutes 

 pieces of fabric in solution of isinglass, glue, gum, and starch, 

 of the best quality, and having a specific gravity of 1*020, 

 at 37° C. These pieces, after being well pressed and dried 

 in the air, were submitted to the temperatures of 80°, 100°, 

 and 126° C, by which they were found to be somewhat 

 weakened, but the action was so very slight, that by exposure 

 to the atmosphere for a few hours, or by washing out the 

 stiffening substance, they were found to have recovered their 

 primitive strength. 



As in calico-printing, oxalic, citric, and tartaric acids, are 

 applied to fabrics when mixed with a stiffening substance, a 

 series of experiments was made with solutions of tartaric, 

 citric, and oxalic acids, thickened with gum and starch, and 

 it was found that the presence of the latter substances greatly 

 increased the action of the above acids, when employed in the 



