1820.] Scientific Intelligence. 465 



any meal or flour, whicli contains but little gluten ; 3, it does 

 not acquire a blue colour, when the wheat flour has undergone 

 any great alteration in its qualities ; 4, when gluten or zimome is 

 kneaded with powdered guaiaciini, a very line blue colour is 

 instantly developed. 



From these observations, Rudolphi concludes that the powder 

 of guaiacum is an excellent reagent for determining whether 

 wheat flour be of a good quality, and whether it has undergone 

 any alteration. — (Giornale di Fisica, Chemica, &c. second 

 bimestre, 1819.) 



IV. Substances capable of developing a Blue Colour in the Alco- 



holic Solution of Guaiacum, 



From the experiments of M. Planche, it appears that the fresh 

 roots of the following plants are capable of producing a blue 

 colour, when introduced into an alcoholic solution of guaiacum: 



Symphytum consolida, Arctium lappa, 



Leontodon taraxacum, Colchicum autumnale, 



Iris germanica, Saponaria officinalis, 



Cichorium intybus, Fumaria officinalis, 



Eryngium campestre, Cochlearea officinalis, 



Nymphgea alba, Scrophularia officinalis, 



Solanum tuberosum, llumex acetosa, 



Bryonia dioica, Scorzonera hispanica. 



Inula helenium, Asparagus officinalis, 



Althsea officinahs, Borago officinalis, 



Daucus carota, Angelica archangelica, 



Glycyrrhiza glabra. Album ca?pe. 

 Napis sativa, 



V. Substances which do not strike a Blue Colour with the Alco- 



holic Solution oj' Guaiacum. 



M. Planche has found that the fresh roots of the following 

 plants do not aflect the colour of the alcohohc solution of 

 guaiacum : 



Rumex acutus, 



Polypodium filex mas, 



Fragaria vesca. — (Journ. de Pharm. vi. ] 8.) 



VI. Indigo. 



The indigo of commerce is veiy far from pure, being mixed 

 with nearly half its weight of foreign substances. I attempted 

 to obtain it in a state of purity by sublimation ; but after a good 

 many trials, I was obliged to renounce that method without 

 accomplishing my object ; for how carefully soever I regulated 

 the heat, I always found that at the subhming temperature, the 

 greatest part of the indigo was destroyed. I succeeded, however, 

 in procuring a few grains of pure indigo by sublimation, which I sub- 



VoL. XV. N° VI. 2 G 



