402 FLAVIN 



horizontally. Similar horizontal beds occur in our tin mines, and they arc sometimes 

 very productive. The carbonas' of the- tin mines near St. In s ;iro little more than 

 flats. Hooson, in his ' Derbyshire Miner,' published in 1747, thus defines a flat : ' it 

 is neither vein, pipe, rake, nor screw.' 



FLATTING. The operation of finishing house-painting so as to prevent the un- 

 pleasant glare -which arises from a surface left in simple oil colour. Tho flatting 

 colour should be incorporated with a largo quantity of spirits of turpentine. This 

 drying leaves a dull surface, which is produced by the resin of the turpentine. Unfor- 

 tunately, from the high price of turpentine, naphtha is now commonly employed. As 

 naphtha contains no resin, the colour is not so permanently placed upon the surface ; 

 it washes off readily, and is liable, after a season, to fall off as dust. This substitution 

 of naphtha should therefore never be allowed. 



FLATTING- IKXXiXi. A mill for rolling out metals into plates. Cylinders of 

 great power arc employed for this purpose. 



FIiAUGHTS. Tools for carding wool, used chiefly in Scotland. 



FLAVIN". A yellow dye-stuff imported from America, and used as a substitute 

 for quercitron bark. It is prepared by dissolving it in hot water, with which it makes 

 a somewhat turbid solution. It should be used when newly dissolved, for if allowed 

 to stand it deposits a brownish-yellow mass, in consequence of its not being all com- 

 pletely soluble in water. If boiled in distilled water until all the soluble matter is 

 taken up, and the clear solution decanted, it soon yields a deposit. The colour pro- 

 duced by flavin is never good until raised. A colour dyed by it weakens gradually 

 when a little sulphuric acid has been added ; but what remaius retains its brilliancy 

 by raising, and in respect of this property it differs from bark. 



Adolph Ott, of New York, makes the following remarks on Flavin in the ' American 

 Chemist': 



' The flavine handed to me for examination came from the Stamford Manufacturing 

 Company, 157 Maiden Lane, New York. It represented a light yellow powder, but 

 sparingly soluble in hot water, and separating again on cooling. The supernatant 

 liquid remained slightly coloured. Warm alcohol, even when diluted, dissolved it 

 quickly; not so ether. Tartrate ofpotassa and copper was not reduced by au aqueous 

 solution, showing the absence of sugar. The solution remained clear on adding a 

 solution of glue, thus indicating the absence of tannin. Sodium-amalgam, when 

 added to an alcoholic slightly-acidulated solution, gave rise to the well-known purple 

 reaction indicative of quercetrin ; this reaction was, by the way, also obtained with the 

 deposit of a decoction of yellow bark. The watery solution of flavine decoloured 

 permanganate of potassa, proving the presence of gallic acid (test of Monier). The 

 absence of tannin and the presence of gallic acid are to be considered as proof thn t 

 the alkaline decoction of the bark had been treated for some time with sulphuric 

 acid. 



The above-mentioned tests satisfied me that the sample was 'a remarkably pure 

 flavine. 



The late Professor Bolley, who first made us acquainted with the method of manu- 

 facture of flavine, discovered tannin and sugar in flavine analysed by him. My speci- 

 men was free from both, but contained gallic acid, the dcrivato of tannic acid. .Since 

 a solution of crude quercitrin assumes a beautiful yellow colour, when protochlor'ule 

 of tin is added, this being not the case with my flavine, I drew the conclusion it -was 

 free from quercitrin. This fact was also to be inferred from the presence of gallic 

 ucid. 



' Prompted by the results of this investigation, I began to search whether them 

 existed other analyses of flavine besides that given by Bolley. My researches in this 

 direction remained without result ; but I obtained, on the other hand, some notes which 

 strikingly illustrate how slow industries sometimes progress when they are unaided l>y 

 science. According to James Napier, who published a book on the art of dyeinir in 

 1853, the flavine must have become a commercial commodity in or about the year 1S.">(). 

 Aside from describing its behaviour towards mordants and vegetable fibres, the author 

 states that it contains 4*4 per cent, ashes. They consisted doubtless of sulphate of 

 soda. Supposing that the dye-stuff had not been washed out, and that to make the 

 decoction the same quantity of water had been employed as prescribed in the patent 

 specification of Leeshing, it would bo very easy to calculate how much soda was used. 

 The quantity was doubtless very large. In 1856 (" Repertory of Patent Invent ions " ) 

 Leeshing, in Glasgow, secured a patent for the treatment of yellow bark. ueM i tin- 

 herb of Reseda lutcola), and flavine, for the purpose of enhancing their colouring 

 power. He terms " quercitriu," the material obtained from <|iien-itn>n ; " llavetin." the 

 one obtained from flavine. His first process consists in boiling the pigment-yielding 

 substance, either with dilute sulphuric or hydrochloric acid, and then washing it out 

 with cold water; a second process consists in previously boiling the dye-woods or dye- 



