Fue 10, 18 86] 
NATURE 
133 
microscope, the plaques, which have a property of sticking to 
the glass slip, will be found to fill the field ; some will be iso- 
lated, some will be in groups; they will now appear glistening 
and granular, and their contours are jagged, becoming more and 
more so as time elapses; finally only a granular mass will be 
found. If, however, a drop of osmic acid be placed on the 
finger before the drop of blood be drawn, all the elements will 
be found presenting their normal appearances, and the plaques 
will be seen as pale homogeneous structures varying greatly in 
size, but for the most part about one-third or one-fourth of 
the diameter of the red corpuscles ; they are biconcave, but not 
as much so as the red corpuscles. Once thus hardened they never 
change their form, but the plaques first referred to will be 
found to alter their form very speedily, and fa7z fassw with these 
changes, processes are seen which run out from the granular 
masses, and when coagulation sets in these processes are nearly 
always found to be continuous with threads of fibrin. The con- 
nection between the breaking down of the blood is not histo- 
logical but chemical. The plaques appear to give up a soluble 
substance which is active in coagulation. This active agent is 
most probably a /id7iz ferment. Fibrin is deposited histologi- 
cally independent of any of the cellular elements of the blood, 
and when the clot is very scant. The fibrin is seen deposited 
as long, needle-shaped, crystal-like bodies. — Studies from 
pee: Lab., Fokns Hopkins Univ., vol. iii, No. 6, May 
1886. 
ON RECENT PROGRESS IN THE COAL-TAR 
INDUSTRY? 
II. 
A Z0-COLOURS.—Amongst the most important of the arti- 
ficial colouring matters may be classed the so-called azo- 
colours. These colours are chiefly bright scarlets, oranges, reds, and 
yellows, with a few blues and violets. They owe their existence 
io the discovery by Griess, in 1860, of the fact that the so-called 
azo-group — N = N — can replace hydrogen in phenols and 
amido-compounds. But it is to Dr’ O. N. Witt that is due the 
honour of having given the first start in a practical direction to 
the chrysoidine class of azo-colours by the discovery of chrysoid- 
ine, and perhaps still more so by the suggestions contained in a 
paper read before the Chemical Society. Dr. Caro, of Mann- 
heim, was also acquainted with several compounds which belong 
to this class at the time Witt published his results, but it does 
not appear that he made practical use of them until Witt intro- 
duced the chrysoidines and tropeolines. To Roussin, of the firm 
of Poirrier of Paris, is due the credit of haying first brought into 
the market some of the beautiful azo-derivatives of naphthol. 
Gniess, therefore, as the original discoverer of the typical com- 
pounds and reactions by which the azo-colours are obtained, 
may be considered as the grandfather, whilst Roussin and Witt 
are really the fathers, of the azo-colour industry. Nor must it 
be forgotten that it is to Perkin we owe the recognition of the 
value of the sulpho group in relation to azo-colours, a discovery 
patented in 1863. Moreover it is interesting to note that 
changes in colour from yellow to red and claret are effected by 
the increase in the molecular weights of the radicals introduced 
as well as by the relative positions occupied by these groups. 
Lndophenol.—Witt is also the discover of a new blue dye-stuff 
termed indophenol, which has been used as a substitute for 
indigo. Certain difficulties, however, have arisen in the adoption 
of this colour on the large scale. The most important use indo- 
phenol is at present put to is for producing dark blues on reds 
dyed with azo-colours, both on wool and cotton. The piece 
goods are dyed a-uniform red first, and then printed with indo- 
phenol white ; for like indigo itself indophenol yields a colourless 
body on reduction, and this being a very powerful reducing agent 
destroys the azo-colour, being itself transformed into indophenol 
blue. The process works with surprising nicety and is very 
cheap. The blue is formed and the red discharged with such 
precision that patterns can be produced in which the blue dis- 
sharge covers a great deal more space than the original red. 
This new printing process was devised by Mr. H. Koechlin, of 
Lorrach. ‘The reds used for the purpose are in the case of wool 
‘he usual azo-scarlets, for cotton Congo red. 
Artificial Indigo.— About five years ago the speaker had the 
.1 A Discourse by Prof. Sir Henry E. Roscoe, M P., LL.D., F.R.S. 
— at the Royal Iustitution, Friday, April 16. 1886, Continued from 
14. 
honour of bringing before this audience! the remarkable dis- 
covery made by Baeyer of the artificial production from coal-tar 
products of indigo blue. Since that time but little progress has 
been made in this manufacture, as the cost of the process, unlike 
the case of alizarin, has as yet proved too serious to enable the 
artificial to compete successfully in the market with the natural 
indigo. 
Through the kindness of a number of eminent colour manu- 
facturers in this country and on the Continent, the speaker was 
enabled to illustrate his subject by a most complete series of 
specimens both of the colours themselves and of their application 
to the dyeing and printing of fabrics of all kinds. His thanks 
are especially due to his friend, Mr. Ivan Levinstein, of Man- 
chester, for the interesting series of samples of cloth dyed with 
known quantities of fifty different coal-tar colours, each having 
a different chemical composition ; also to the same gentleman, 
and to Messrs. Burt, Boulton, and Haywood, of London, for the 
interesting and unique series of specimens indicating the absolute 
quantities of products obtainable from ove tox of coal, as well as 
for much assistance on the part of Mr. Levinstein in the prepara- 
tion of the experimental illustrations for this discourse. To Dr. 
Martius of Berlin for a valuable series of colours, especially the 
well-known Congo red, made by his firm, including samples of 
wool dyed therewith, he is also much indebted. For the inter- 
esting details concerning indophenol and its applications the 
speaker owes his thanks to Dr. Witt and M. Koechlin. 
Coal-tar Antipyretic Medicines.—Next in importance to the 
colour industry comes the still more novel discovery of the 
synthetical production of antipyretic medicines. 
Up to this time quinine has held undisputed sway as a febri- 
fuge and antiperiodic, but the artificial production of this 
substance has as yet eluded the grasp of the chemist. Three 
coal-tar products have, however, been recently prepared which 
have been found to possess strong febrifuge qualities, which if 
still in some respects inferior to the natural alkaloids, yet possess 
most valuable qualities, and are now manufaciured in Germany 
at Hochst and at Ludwigshafen in large quantity. And here it 
is well to call to mind that the first tar colouring-matter dis- 
covered by Perkin (mauve) was obtained in 1856 during the 
prosecution of a research which had for its object the artificial 
production of quinine. 
In considering the historical development of this portion of 
his subject, the speaker added that it is interesting to remember 
that the initiative in the production of artificial febrifuges was 
given by Prof. Dewar’s discovery in 1881 that quinoline, the 
basis of these antipyretic medicines, is an aromatic compound, 
as from it he obtained aniline. Moreover that Dewar and 
McKendrick were the first to observe that certain pyridine salts 
act as febrifuges. So that these gentlemen may be said to be the 
fathers of the antipyretic medicines, as Witt and Roussin are of 
the azo-colour industry. 
Katrine, the first of these, was discovered by Prof. O. Fischer, 
of Munich, in the year 1881, whilst engaged on his investigations 
of the oxyquinolines. The febrifuge properties of this substance 
were first noticed by Prof, Filehne, of Erlangen. Kairine is 
manufactured from quinoline, a basic product derived from ani- 
line by heating it with glycerin and nitrobenzene by the following 
process. When treated with sulphuric acid, SO,Hs, it forms 
quinoline sulphonic acid, and this when fused with caustic soda 
yields oxyywinoline, which is then reduced by tin and hydro- 
chloric acid into tetrahydroxyquinoline, and this again on 
treatment with C,H,Br yields ethyl-tetraoxyquinoline or kairine. 
The lowering of the temperature of the body by this compound 
is most remarkable, though, unfortunately, the action is of much 
shorter duration than that effected by quinine itself ; but on the 
other hand, with the exception of its burning taste, it exerts no 
evil effects such as are often observed after administration of large 
doses of quinine. The commercial article is the hydrochloride, 
the price is 85s. per Ib., and the quantity manufactured has lately 
diminished owing to the discovery of the second artificial febri- 
fuge, antipyrine. 
The following graphical formula shows the constitution of 
kairine :— 
/ CH,CH, 
BEE: 
Ey Cl 
t On Indigo and its Artificial Production,’ Proc. Roy. Zust., May 27, 
1881. 
