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Letter from Professor Johnston, inclosing one from Professor 

 Mulder of Utrecht. 



To the Editor of the Edinburgh Philosophical Journal. 



Edinburgh, 2^d March 1847. 

 My Dear Sir, — You will oblige me by inserting, in your 

 ensuing Number, the enclosed translation of a letter I have 

 l*eceive(l from Professor Mulder of Utrecht. The protein 

 compounds, at the present moment, are of much interest 

 among chemists ; and it is of importance that parties who 

 have not closely attended to the matter, should be made 

 aware of the precise point in dispute between Mulder and 

 Liebig, and of the exact state of our knowledge upon the 

 subject. In this letter, Mulder has not given any of his new 

 researches, which have already, as he informs me, made him 

 acquainted with many new facts. The views he advances, how- 

 ever, are novel, and, so far, as satisfactory as they are beau- 

 tiful. I am confident that, whatever the truth may prove 

 to be in this matter, Mulder will publish it; and that no 

 fear of personal consequences will ever cause him to deviate 

 from that sincere path, by which alone the investigation of 

 natural science can be successfully prosecuted. — Believe me, 

 my dear Sir, yours very sincerely, 



James F. W. Johnston. 



Utrecht, \2th March 1846. 

 My Dear Friend, — You will probably have read in the '* An- 

 nalen der Chemie und Pharmacie" for January 184:7, that Liebig 

 now endeavours, in a covert way, to adulterate protein with sul- 

 phur under another form than that in which he originally stated it 

 to exist. The question was first, — and this is the true state of the 

 subject, — Can albumen, fibrin, &c., when treated with potash and 

 acetic acid, yield a precipitate which neither discolours silver when 

 heated upon it with potash, nor produces sulphuret of lead when 

 heated in a solution of acetate of lead ? Liebig has denied this 

 (Ann.^ Jan. 1846), and Laskowski likewise. According to him, the 

 additional application of oxide of bismuth or silver was required for 

 this purpose (Jnn., Mar. 1846.) I had asserted, that the latter 

 was unnecessary, and that the reaction of the sulphur upon silver 

 could be made to disappear by the use of potash alone. 



This point demands an open publication, and not one given in an 

 obscure and involved manner. Whether Liebig, or some one else, 

 lias been mistaken, has nothing at all to do with truth or its publi- 



