126 CORRESPONDENCE. 



species of Isatis and Wrightia. Some think that the species of Rudlia 

 yielding the Roam of Assam is R. comosa. Wall. : or the R. eucoma, Steudel. 

 It is doubtless the product of more than one species. 



Singapore Blue. — From an acanthaceous plant at Singapore the 

 Chinese extract, for their own use, a blue dye which Mr. Seemann thinks 

 may be identical with Roam. 



Isprtjck. — A blue dye yielded by a species of Delphinium is in use in 

 Scinde under this name. Whether used as an extract, or dyed from the 

 plant itself, we are not informed. 



Mouringhy. — The wood of Moringa pterygosperma is used as a blue dye- 

 stuff in India. Its use is very local and unimportant, since it offers no 

 advantages superior to indigo. 



Maharanga. — A blue dye obtained from Maliaranga emodi is employed 

 in Nepal. Under the name of Maliaranga the roots are imported into other 

 parts of India, from Gosainsthau and probably from Thibet. 



From this enumeration it will be seen that the majority of the blue dyes 

 of China and India are either true indigos, or partake very much of their 

 nature. There are but few novelties to interest the home dyer, unless he 

 coidd obtain and experimentalise upon the Roum of Assam, the Siaou Ian 

 or Tien-cliing of China, or the Taroum-akkar of Sumatra. 



We purpose at a future opportunity enumerating the other dye-stuffs of 

 China and India which are not included in the present and two previous 

 papers. 



Correspondence, 



To tlie Editor of the " Technologist." 

 Sir, — I congratulate you on your undertaking the establishment of the 

 Technologist, although you are, according to my opinion, fifty years 

 behind. I am a German, and we have done such things already fifty years 

 ago. You have done the same thing isolated, as did Dr. Ure, G. Dodd, 

 and M'Culloch, but you have had neither a real polytechnical college, nor 

 general works for technological purposes. There can be no doubt that the 

 single branches of science are very well taught by extremely well-versed 

 gentlemen in the different colleges of the universities of Great Britain ; but 

 there seems to be till now no private teaching of the whole science. You 

 know as well as I do myself, that the Polytechnical School at Paris, founded 

 by Napoleon I., is destined exclusively for the training of young officers ; 

 that the English institution of that name has come down to a mere place of 

 amusement ; and that the Panopticon for Science and Arts has been 

 closed, because its numerous visitors were not inclined either for science or 

 for arts. The only institution deserving its name is the Polytechnical 

 School at Vienna, erected in the year 1820, where they have a private 

 college of technology, under the auspices of Professor Altmiiller. The 

 author of these lines has visited the said institution, getting there the 



