PRELIMINARY NOTES ON THE CHEMISTRY OF THE LATEX OF CALOTROI'IS PROC'ERA 



91 



partly soluble in cold water, l)ut soluble in liot. This solution gives a deep blue colour 

 with the diluted sulphuviir aciil reagent. If water be added to the alcoholic solution 

 previous to evaporation of the alcohol, a bright yellow, acrid resin is obtained. 



On reducing the coagulated latex with zinc dust and acetic acid, a liquid is obtained, 

 which, after removal of the zinc by sulphuretted hydrogen, gives no coloration with 

 sulphuric acid, unless previously reoxidised. Concentration of this liquid leaves an 

 amorphous brownish residue, and a considerable crop of silky needle-like crystals of 

 calcium sidphate. Extraction of the licpiid with solvents i-evealed no organic 

 substance of a crystalline nature. 



The following tables give in sunnuary form Uic results of the experiments carried 

 out to gain some information as to the character of the substance in the latex to which 

 the blue coloration, produced by sulphuric acid and an oxidising agent, is due. From 

 100 c.c. to 200 c.c. of the latex were taken for each experiment, so that concentrated 

 solutions were obtained. 



'l'AI',l,K A 



.Summary 

 of results 



Latex 



Added 4 voUuncs of water .■iiid ;i few drops of acetie .acid, aud heated on the water-batli to eoagulation. 

 Straiaed and filtered. 



QuTTA-PEncHA, and 

 associated resinous 

 l)od1es, etc. 



Filtrate, t Added sliKlit i^xeess of neutral lead acetate, and tiltered. 



Heavy White 

 Pbeoipitate. 

 Washed well 

 with water and 

 decomposed witli 

 dilute sulphuric 

 acid. Solution ° 



Filtrate (aj.f Added slight excess of basic lead acetate, 

 and tiltered 



Precipitate. 

 Washed well 

 with water and 

 decomposed with 

 dilute sulphuric 

 acid. Solution ° 



Filtrate (b).t Added excess of am- 

 monia = bulky yellowish-white ])reeipi- 

 tatc. Filtered 



Precipitate (d). 

 Washed, and de- 

 composed with 

 dilute sulphuric 

 acid. Solution t 



Filtrate (e) ° 



t indli:.ates positive reaction with reaf<ent 

 ° ,, negative ,, ,, 



TABT,R r. 



TjATKx 

 Added 4 vuluuies of water, and a few drops of acetic, acid, and coasnlatod. Strained and filtered. 



Gutta-percha, 

 and associated resinous 

 bodies, etc. 



Filtrate. t Digested on the water-bath for several hours with animal charcoal, 

 and filtered 



Charcoal Eesidue (a) 



Washed with cold water, dried over sulphuric acid, 

 a7ul extracted thoroughly with absolute alcohol. 



Alr-oholie ^oliition.t 



Filtrate" (b) 



indicates positive reaction with reagent 

 „ negative „ „ 



