592 REPORT— 1886. 



a dilute aqueous solution of bromine in an alcoholic solution of the base. It forms a 

 soluble monacetyl and an insoluble diacetyl derivative in form of silky needles. The 

 hydrogen of the amidogen groups may be replaced b}' two or four methyl groups 

 forming secondary bases resembling tolidin, and melting at 69° and 81° respectively. 

 Further union -with methyl iodide gives the ammonium salt, crystallising in red 

 needles, from which the hydrate may be obtained by silver oxide. 



With chloroform by no experiment could even traces of an isocyanide be 

 obtained. 



Carbon disulphide forms a thiourea but yields no isosulphocyanide. The base 

 unites directly with cyanogen to form a dicyanogen compound of red colour and 

 very insoluble. With urea it unites directly, evolving ammonia, forming a com- 

 pound urea. The same substance can be obtained with phosgene gas, hydrochlorate 

 of tolidin being simultaneously formed. The diuitrodiacetyl crystallises in yellow 

 needles, soluble in hot nitrobenzol. Strong caustic potash forms from this the 

 nitrotolidin in red plates soluble in alcohol. 



Nitrous acid gives a tetrazoditolyl from which all the azotolidin colours are 

 derived. Their general formula may be represented by 



CH3-CgH3-N = N-R 

 CHj-C^Hg-N^^N-R 



where R represents more or less complex aromatic acids or their sodium salts. 

 Thus in Congo red, R is the sodium salt of naphthylaminesulphonic acid ; in 

 chrysarine yellow it is sodium salicylate ; in azo blue B-uaphtholsulphonic acid. 

 These colours are peculiar, in that they alone of aU the artificial dyes are capable 

 of dyeing cotton and wood fibre directly, i.e., without the intervention of a mordant. 

 Cotton fibre boiled in tolidin hydrochlorate, washed, dried, and dipped first in 

 dilute nitrous acid, and then in some of the above acids is permanently coloured of 

 particular dye formed by that acid, thus showing that the tolidin probably unites 

 with the oxycellulon of the cotton, and so acts as a mordant. This is rendered 

 further probable, as when once dyed by one of these colours cotton fibre will form 

 mixed colours directly with such basic dyes as fucsin, methyl blue, &c. 



TUESDAY, SEPTEMBER 7. 



The following Papers were read : — 



1. On the Treatment of PhospJwric Crude Iron in Open-hearth Furnaces. 



By J. W. Wailes. 



The great importance of a process dealing with phosphoric iron must be 

 measured by the extent of the deposits of ore yielding phosphoric pig. These 

 deposits in Europe exceed by ten or twelve to one the deposits of ore yielding purer 



pig- 



The amount of phosphorus that can be allowed in finished steel may be taken 



at not more than one tenth per cent., though this is more by about half than 



manufacturers care to deal with. 



The softer and purer kinds of steel, where great ductility is required, shoidd 

 contain as little phosphorus as possible, the efletft of this element being to render 

 iron and steel brittle at ordinary temperatures. 



A description of puddling was then given (illustrated in the diagrams), showing 

 the furnace and the reactions that take place during the process, and it was con- 

 tended that the manual labour of puddliug was rendered necessary by the limited 

 range of heat obtainable in puddling furnaces, which is not sufiicient to retain iron 

 after it has parted with a large proportion of its alloys in a molten condition, so 

 that the metal has to be removed from the furnace in a spongy state. A com- 

 parison was then drawn between the process of purifying phosphoric iron by 



