108 PROCEEDINGS OF SECTION B. 



The brown stain produced by the raspberry juice in question is 

 not likely to be mistaken for that produced by artificial colouring 

 matters, such as those which would be used for colouring raspberry 

 juice. These would naturally be of a red colour, and might be expected 

 to dye the wool red. It was thought, however, that it would be advis- 

 able to ascertain, if possible, the circumstances under which raspberry 

 juice was capable of communicating this brown colour to the final 

 wool. 



The colouring matter behaved as a dye of an acid character, none 

 of the samples examined giving any reaction from the wool originally 

 placed in the alkaline solution ; all the following experiments were 

 therefore carried out on acidified solutions. 



Sample No. 1, which gave the reaction, was made from Tasmanian 

 raspberries and had been acidified with 5 per cent, of acetic acid as a 

 preservative. It had been kept in a wooden cask, and it was thought 

 at first that the colouring matter might have been dissolved from the 

 wood. It was found, however, that the brown stain coidd be produced 

 from raspberry juice which had not been in contact Avith wood at all. 

 The acetic acid used as a preservative was colourless, and when mixed 

 with fresh raspberry juice and tested by the wool test gave no colour 

 to the final wool. 



Sample No. 1, using 50 c.c, gave a brown stain to the final wool. 



Samples Nos. 2 and 3 were obtaired from different sources, had no 

 acetic acid added to them, but had been sterilized by heat and kept 

 in tightly-stoppered bottles. Using 50 c.c. neither of the samples 

 produced more than a very slight dirty stain on the final wool. 



Sample No. 4 was obtained from the same source as that which 

 gave the reaction, but no acetic acid had been added to it. On testing 

 50 c.c. in the same way a brown stain was communicated to the final 

 wool similar to that produced by sample No. 1. 



At the same time a fresh sample of No. 1 was tested under exactly 

 the same conditions, and the same result was obtained as - with the 

 original sample. 



Some fresh raspberries were next obtained from Tasmania from the 

 grower who supplied sample No. 1, and the juice was extracted in two 

 stages. The raspberries were placed within four folds of linen and 

 pressed (1) between the hands, giving 730 c.c. of juice ; and (2) in a 

 screw press, giving 115 c.o. It was thought that the screw press 

 might remove some colouring matter from the residue of the seeds, 

 &c., which might account for the brown stain. Both solutions were 

 filtered through paper and were found to be acid. On testing 50 c.c. 

 of each solution neither gave any decided colour to the final wool. 



The two solutions were then mixed (sample No. 5), a portion 

 taken, acidified with 5 per cent, of acetic acid, using the same acid as 

 that used in sample No. 1, and tested in the usual way. A faint colour 

 only was communicated to the final wool. 



