46G 



Scientific Intelligence, 



III. A Treatise on Neiu Philosophical Insiriments, for various 

 purposes in the Arts and Science^, ivith Experiments on Light 

 and Colours. By David Brewster, LL.JD. F.R.S.E.] We 

 shall notice this excellent work more particularly in a future 

 Number of the Annals. 



Part I. of Vol. n. of the Transactions of the Linnaean Society 

 Is also publishedj and will come under our notice in a future 

 Number, 



Article X« 



SCIENTIFIC intelligence; AND NOTICES OF SUBJECTS 

 CONNECTED WITH SCIENCE. 



I. Method of taking Ironmoulds out of Cottono 

 Every body knows that cottons of all kinds are apt to receive 

 a dirty yellowish, or orange stain, from iron, which, if allowed 

 to remain, gradually corrodes the cloth and forms a hole. At 

 first these stains are easily removed by means of muriatic acid, 

 or any other diluted acid (except vinegar) ; but, after they have 

 remained for some time, acids have no effect upon them. It may 

 be acceptable to my readers to point out the method of removing 

 these moulds in such inveterate cases. 



The iron in them is in the state of red oxide ; and it appears, 

 from various facts well known to chemists, that the red oxide of 

 iron has a much greater affinity for cotton cloth than the black 

 oxide. The object in view, therefore, should be to bring the 

 iron in the mould to the state of black oxide ; after which, 

 muriatic acid will easily remove it. Now there are two methods 

 of doing this ; both of which in the present case answer the 

 purpose completely. The first is to touch the mould with the 

 yellow liquid formed by boiling a mixture of potash and sulphur 

 in water, called hydrogureted sulphuret of potash by chemists. 

 The mould becomes immediately black, and the action of diluted 

 muriatic acid immediately effaces it. The second method is to 

 daub the mould over with ink so as to make it quite black. After 

 this muriatic acid takes it out, as in the former case. 1 conceive 

 that this is occasioned by the action of the nutgalls in the ink, 

 which reduces the ii-on in the mould to the state of black oxide, 



jJL Compositio?i of Azote. 

 Professor Berzelius has announced, in a letter to a celebrated 

 chemist in Londv o, that he has satisfied himself, by a mode of 

 calculation which he has not explained, that azote is a compound 

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