Frilzsche on the Action of 'Potassa on Indigo-blue. 191 



BaO + 2aq. It is isomeric with Delalande's camphen- 

 sulphate, &c. — {Annates de C/iim. et de Phys. III. t. i. p. 60.) 



On account of the great length of this memoir, many im- 

 perfectly examined, and not as yet analysed substances, have 

 been passed over in this abstract without notice. Liebig's 

 remarks, moreover, showing that the French type is nothing 

 more than radical, could not be extracted without encroach- 

 ing too much on other important papers. 



On the Action of Potassa on Indigo-blue, 



Fritzsche has continued his researches on Anilin, a sub- 

 stance which had been previously described by Unverdorben 

 under the name of Crystallin, as has been already mentioned. 

 (Notices, Phil. Mag.,s. 3,vol.xviii.p.280.) The action does not 

 commence until the potassa solution is very concentrated and 

 has been boiled some time ; the boiling point must be as high 

 as 150°. If the solution be kept at this temperature, and pure 

 indigo-blue added from time to time, the whole is dissolved, 

 forming a yellowish red liquid, in which, after a time, crystals 

 are formed ; it is then better to stop the operation and allow 

 the whole to crystallize. By this operation hardly a trace of 

 any volatile substance is formed, and no gas evolved. A 

 small quantity of a dark-coloured substance is formed with 

 the yellow potash salt, from which it cannot be separated ; it 

 appears to be an accidental product. If the whole crystallized 

 mass be treated with water, this dark coloured substance 

 causes a formation of indigo-blue, but the excess of potassa 

 also acts on the yellow salt, and indigo-blue is precipitated. 

 It is better therefore to saturate the greater part of the potassa 

 in the solution with an acid. A bluish green precipitate is 

 formed, and by filtering a golden-yellow fluid is obtained, out 

 of which acids precipitate a voluminous flocky reddish-brown 

 body — chrysanilic acid. The colour of this new acid is simi- 

 lar to that of kermes mineral. It is not at all crystalline, as- 

 sumes a darker colour by drying. It is very little soluble in 

 water, easier soluble in alcohol ; from a concentrated solution 

 in a mixture of water and alcohol it may be obtained in a 

 crystalline state. It dissolves in alkalies with a golden-yellow 

 colour, but care must be taken not to use an excess of alkali, 

 for then the fluid becomes green. The metallic salts are in- 

 soluble, lead and zinc salts are of a beautiful red colour. The 

 formula is not as yet determined ; the results obtained do not 

 agree well with one another. By dissolving chrysanilic acid 

 in dilute sulphuric acid two new bodies are formed, one of 

 which crystallizes out on cooling, the other remains dissolved. 

 The soluble one has received the name of Anthranilic acid, 



