222 Dr. Schunck on Colouring Matters. 



tract of madder contains all the free colouring matter of the root, 

 and acts in dyeing in the same way as madder itself, it was evident 

 that by trying the constituents of this precipitate in conjunction with 

 one another, both in a free state and in combination with lime, a 

 correct view of the part performed by each would be arrived at. 

 Having therefore taken a piece of calico on which three mordants 

 had been printed, one for red, one for purple, and one for black, 

 in alternate stripes, each stripe being one quarter of an inch broad, 

 and having intervals between them of the same width, it was divided 

 into pieces of six inches by three, and one of these pieces was taken 

 for each of the following experiments. As the tinctorial power of 

 alizarine is very great, so great that one quarter of a grain was 

 enough to over-dye one of these pieces, I took one or two grains 

 of crystallized alizarine, dissolved it in a measured quantity of water, 

 to which a little caustic alkali had been added, and was then able 

 to divide the solution into portions corresponding to quarters, 

 eighths, and sixteenths of a grain, so that by precipitating one of 

 these portions with muriatic acid, filtering and carefully washing, 

 I obtained small quantities in a state very well adapted for dyeing. 

 By treating one of these quantities while on the filter with lime-water, 

 and washing out the excess of lime, I obtained small quantities of 

 the lime compound of alizarine for the same purpose. The same 

 process was used for obtaining small quantities of rubiacine, alpha- 

 resin, beta-resin, peciic acid and rubian, and their lime compounds. 

 Each experiment was performed with the same quantity of water, 

 at as nearly as possible the same temperature, and occupied the same 

 length of time, viz. half an hour. The substances used, and their 

 quantities, were as follows : — 



1. ^ grain of alizarine. 



2. Y^g gr. alizarine. 



3. Jg. gr. alizarine and -^-^ gr. alizarine in combination with lime. 



4. -^^ gr. alizarine and ^^ gr. alizarine in combination with lime. 



5. ^ gr. alizarine and ^ gr. rubiacine. 



6. ^ gr. alizarine and ^ gr. rubiacine in combination with lime. 



7. -^2 g^' alizarine and ^-^ gr. rubiacine in combination with lime. 



8. ^ gr. alizarine and ^ gr. pectic acid. 



9. ^ gr. alizarine and ^ gr. pectic acid in combination with lime. 



10. ^ gr. alizarine and ^ gr. alpha-resin. 



11. ^ gr. alizarine and ^ gr. alpha-resin in combination with lime. 

 \t. ^ gr. alizarine and ^ gr. beta-resin. 



13. ^ gr. alizarine and ^ gr. beta-resin in combination with lime. 



14. ^ gr. alizarine and ^ gr. rubian. 



15. ^ gr. alizarine and ^ gr. rubian in combination with lime. 



Now the following results were obtained : — No. 1 was every- 

 thing that could be desired in regard to all the colours. No. 2 was 

 of course only half as dark. No. 3 was lighter than No. 1, and the 

 white parts had a pink hue. No. 4 was a little darker than No. 3, 

 but not as dark as No. 1. No. 5 was much inferior to No. 1 ; the 

 red had an orange hue, the purple a reddish cast, and the black was 



