go Colouring Matters Derived from Diazo Compounds. {Sus Neve,
Assay of platinum alloys containing base metal, silver, |  Prerident—Warren de Ia Rue, F.R.S. .
platinum, gold, and iridosmine. Vice-Presidents—The list remains unaltered with the
Charge Pt alloy 200 Mg, pure Ag 150 Mg, or sufficient insertion of J. H, Gladstone and omission of Warren de
to produce perfect cupellation (exact weight.) la Rue.
Wrap charge in sheet lead and cupel. Weigh button. Treasurer—W. J. Russell.
Loss = base metal. Secretaries—W. H. Perkin, H. E. Armstrong.
Flatten button, anneal, roll out thin, anneal again, and Foreign Secretary—Hugo Miler,
make into cornet as in gold bullion assay. Introduce Other Members of the Council—M. Carteighe, A, H,
cornet into parting flask and part with concentrated Church, W. N. Hartley, C. W. Heaton, E. Riley, W,
H,S0,. Wash, anneal, and weigh. Loss from previous Chandler Roberts, T. E. Thorpe, W. Thorp, J. L. W,
weight=Ag in original alloy + Ag added for cupellation, Thudichum, W. A. Tilden, R. V. Tuson, R. Warington.
Alloy cornet with at least twelve times the amount of The following gentlemen were elected auditors for the
Ag that there is Pt present, and, as before, form cornet year :—R. J. Friswell, J. Spiller, and J. M. Thomson.
and part first with HNOj sp. gr. 1°16, and then HNO; sp. The PRESIDENT then called on Dr. Otto N. WrTT to
gr. 1-26. Wash thoroughly, anneal in annealing cup, and read a paper ** On Colouring Matiers Derived from Di.
weigh, Loss=Pt. azo-compounds.” During the last three or four years
Treat residue with aqua regia, obtain Au by loss—the aniline colours have come into euch general use as to, in
residue is irridosmine. many instances, replace the old costly artificial and
Time to complete assay in duplicate, 2 hours 45 minutes. natural dyes. Although there has been known for some
The quality of Ag added should at least be sufficient, timeagreatvariety of magenta, violet,and blue aniline dyes,
so that after the addition the Ag in the alloy willbe to the green and yellow dyes were almost unknown until quite
Auas3:iI. recently, Three years ago the author, in a paper read
As platinum and irridosmine add greatly to the infusi- before the Society, indicated a theory as to the relation
bility of the compound, silver in sufficient quantity must Jetween the chemical constitution and the colouring
be added to prevent * freezing’ and give a perfect cupella- power of aromatic substances. In this paper he pointed
tion. Any large excess over these requirements is to be out that there existed a series of compounds, the colour
avoided—first, because the residue, after parting, will in of which was in close relation to their chemical constituthat
 case be non-adherent and in a more or less fine state tion. The first link of this series is azo-benzene,
of subdivision, which may occasion loss in washing by CeHs—N=N—CgH;. This substance is of a deep yellow
decantation ; second, the larger the button cupelled the colour, but being devoid of ‘salt forming groups is not
more difficult it is to obtain a good cupellation, and the applicable for dyeing, By introducing amido. or oxygreater
 the loss of Ag during the process. It may, forthis groups, compounds can be formed having strong affinities
reason, sometimes be necessary to use only 100 Mg of the for textile fibres, which increase with the addition of each
alloy for assay instead of 200 Mg, as above. salt-forming group into the molecule. At the time this
The cupellation should take place at a moderate tem. paper was read amido-azo-benzene and tri-amido-azoperature,
 until near the ¢ blick,” when the assay should benzene were the only dyes of this class known; the first
be thrust back into the hottest part of the furnace to pre- was of a beautiful bright yellow colour, but fugitive; the
vent “freezing.” The button #ust remain in the muffle second was fast, but dull. Since that time the interuntil
 all the Pb is gone. mediate di-amido-azo-benzene has been formed and
In parting with H,80y, boil for several minutes. In named chrysoidin, which combines the beauty of the
other respeds, this operation is identical with the gold. monamido- and the fastness of the tri-amido-bodies.
bullion assay. Any large excess of Ag over twelve times The preparation of chrysoidin is then given. Griess has
the amount of Pt in alloy is to be avoided, as it causes the shown that not only can amido-azo-compounds be obresidue,
 after parting, to be too fine and float, thereby iained, but that the oxy-derivatives of azo-benzene and
occasioning loss in washing. Insufficient Ag is ever >Other similar bodies can be prepared by the a&ion of diworse,
 as the Pt will then be only incompletely dissolved. 1zo-compounds on the corresponding phenols; these oxy-By
 the above method I was successful in obtaining very Jerivatives are also dyes; so that these di-azo-compounds
closely duplicating results, was enabled to do away witk 1ave opened out an almost inexhaustible mine of new
all precipitation and filtering, no apparatus being required, and beautiful dyes. Since Hofmann’s paper on chrysoidin
except that necessary for the gold and silver bullion assay, .nvestigations on this class of compounds have been set
and, what is only second in importance to accuracy, attained on foot in the laboratories of almest ail aniline colour
results with the least expenditure of time. Mr. William manufacturers. The patents taken out for their produ&ion
Strieby, A.M., E.M., has assisted me materially in perfect- are constantly increasing in number. In consequence of
ing this assay, and employed it in his own work with his connection with Messrs. Williams, Thomas, and
equally satisfactory results. Dower the author has not been able to carry out his
I present the above to your readers, hoping it may prove original intention of describing fully the preparation and
of service to some engaged in similar work.—~Engineering properties of all his new azo-colours. The prototype of
and Mining Journal. these compounds is chryspidin, The author has already
given a description of the properties of this substance in
Fourn. Chem. Soc., ii., 457, 1877. He has since prepared
in a pure state the following analogous substances closely
resembling the typical produ& :—Ortho-tolyl-phenylenchrysoidin,
 para-tolyl-phenylen-chrysoidin, phenyl-toluylen-chrysoidin,
 ortho-toluylen-chrysoidin, para-tolyl-toluylen-chrysoidin,
 phenyl-toluylen-chrysoidin sulphonic acid,
a-naphthyl-phenylen-chrysoidin sulphonic acid, a-naphthyl-toluylen-chrysoidin
 sulphonic acid. Each basic
colour has an acid counterpart similar in shade and constitution
 but containing hydroxyl- in place of amido-groups.
The acid counterpart of chrysoidin has been prepared by
Baeyer and Fager, and studied by Typke. This compound
is a beautiful but unstable dye. The author therefore
introduced a sulpho-group into its molecule by treating
resorcin with para-di-azo-benzene sulphonic acid. The
substance has since been described by Griess. Its constitution
 ~~ that  meta-di-azo-oxy-benzene sulphonic

Dr. J. H..GrapsToNE, F.R.S,, President, in theZChair.
AFTER the confirmation of minutes, &c., the following
certificates were read for the first time :—W. North, F.
Podmore, W. Y. Gent, W. Radford.
‘The list of Officers for the ensuing year as proposed by
the Council was then read —