FEBRUARY 4, 1897 | 
NATURE 
319 
The process may be described in a very few lines. In the 
first place a negative is taken on a gelatine plate, which 
has been specially prepared. The plate is developed and 
fixed in the ordinary way, and the image appears of the 
same character as if taken on a good density-giving plate. 
A transparency (a positive) is next taken on a similar | 
plate from this negative, or a silver print made on 
specially prepared albumenised paper, on either of which 
the colour process is worked. The colouring is of a very 
simple nature. There are three dyes—a crimson-red, a 
grass-green, and a very good blue, all in solution, and 
mixed with some other ingredients besides water. There is 
also what we may call a mordant in the shape of a colour- 
less liquid containing, I should say, albumen and salt. 
This last liquid is brushed copiously over the face of 
the positive (or the silver print), and the blue dye applied 
alittle ata time. If the light be good (and it was stated 
that the colouring must take place in good daylight), the 
blue dye rapidly takes hold of those portions of the surface 
which represent in monochrome what are blues in the 
original. For instance, a china vase will take the blue 
tint, and the face or hands a faint amount of the same 
colour. The green dye is applied in the same manner, 
and the greens in the original make their appearance in 
the positive, and so with the red. Finally the print or 
positive presents a picture in colours, underlying which 
is the dark brown silver image. It appears as if the 
image took up selectively these three colours ; but why 
it takes them up, it is hard to see. I have by me a por- 
trait done in the manner described, and the negative has 
evidently been retouched with the pencil. It is difficult 
to understand why a pencil mark should be the cause of 
selective absorption of the colours, or that a special 
plate should be necessary. That the success of the 
process does not depend upon the inventor's manipula- | 
tion is quite evident, for negatives were taken by Sir H. T. 
Wood, quite independently of him, but of course on pre- 
pared plates given him for the purpose, and from these he 
made positives. These last, when treated with the colour- 
ing matter, gave the correct colours of the original. Still 
I am somewhat sceptical—I believe it is my failing to be 
so—and I shall not be satisfied till I get the plates that 
have been promised me by the inventor (M. Chassagne), 
and taken negatives of certain test objects which will be 
unknown to the inventor. If he can reproduce their 
colours it will have to be without any reference to the 
amounts of silver which ordinarily indicate the colour in 
the original, for in the negatives sent every colour will be 
represented by approximately an equal density. Some 
few years ago a powder process was seen by Mr. C. V. 
Boys, in which three coloured powders selectively adhered 
to the surface of paper. The paper was prepared with 
some glutinous substance and bichromate of potash, and 
which remained more or less tucky according to the 
amount of exposure to light it received. These three 
powders, a red, a green, and a blue, | believe, if applied 
in a certain order, adhered to the print, and gave 
approximately correct results of colour, though no special 
negative was required. Whether this new process now 
‘described depends on any similar grounds, it is hard to 
say at present. 
The point that strikes me in the latest process is that 
it is only from a specially prepared negative that a print 
suitable for colouring can be made. Were it the negative 
which took up the colour, one might understand the 
matter better. To me at present the process as stated 
is a mystery ; but if it does all that it is claimed for it, 
it must be a great success, and the theory of it will have 
to be investigated in a thoroughly scientific manner. At 
present the details are a secret; but I am given to 
understand that the seal of secrecy will be withdrawn 
before long, as a patent is applied for. We shall then 
be able to ascertain on what principles the process is 
worked. W. DE W. ABNEY, 
NO. 1423, VOL. 55] 
\ 
BRITISH ASSOCIATION MEETING IN 
TORONTO. 
I.—LOcCAL ARRANGEMENTS, 
5 Ree: various special Local Committees, organised to 
_make preparations for the British Association 
meeting, to take place in Toronto this year, have now, 
after a year’s work, to report very satisfactory progress 
in the arrangements for the occasion. In the case of 
some of the Committees, their work may be considered 
as finished. The special Committee on Finance, for 
Instance, has secured promises of financial aid to the 
extent of 5700/. from the Governments of the Dominion 
of Canada and the Province of Ontario, and from the 
Toronto City Council. This sum will, it is believed, be 
fully sufficient for all the expenses of the meeting, 
which, owing to the special circumstances of the occa- 
sion, must be larger than those of any meeting in Great 
Britain. 
The Committee on Rooms also has, for the present, 
finished its labours. According to its report, which has 
been adopted by the Local Executive Committee, the 
reception room, general offices, and the rooms for the 
sectional meetings are all to be in the various lecture- 
rooms and laboratories of the University of Toronto and 
of the School of Practical Science. As the buildings of 
the University and School are in the centre of the city, 
and within less than five minutes’ walk from the electric 
car line which communicates with all parts of the city, 
the selection offers every convenience in the way of con- 
veyance. The rooms selected are large and well adapted 
for the purposes assigned, and all are within a short 
distance of each other. Sections A and H (Mathemat- 
ical and Physical Science and Anthropology) will occupy 
lecture-rooms in the main building of the University, 
Sections D, land K (Zoology, Physiology and Botany) 
are allotted rooms in the Biological building, Section B 
(Chemistry) will be placed in the Chemical building, 
Section E (Geography) in the general reading-room of 
the University library, while Sections C, F and G 
(Geology, Economics and Mechanical Science) are to be 
given large rooms in the University Y.M.C.A. building, 
Students’ Union building, and in the School of Practical 
Science respectively. The only building to be used by 
the Association, and not situated on the University 
grounds, is Massey Hall, in which will be delivered the 
President’s address and the evening lectures. It is 
capable of seating 4000 persons, and has _ splendid 
acoustic properties. 
One of the conversaziones will be held in the main 
building of the University ; the other will, it is expected, 
be given in the new buildings of the Provincial Legis- 
lature. A number of gentlemen have kindly offered to 
give garden parties, while the Faculties of Trinity College 
and Victoria College have arranged to hold receptions. 
The various Clubs in the city will be open to the members 
of the Association. 
The arrangements for conveyance are not yet com- 
pleted, but the concessions already made by the Steam- 
ship and Railway Companies may be announced. The 
Canadian Steamship Companies, the Allan, Dominion 
and Beaver Lines (Liverpool and Londonderry to Quebec 
and Montreal) have granted to members of the Associa- 
tion considerable reductions in rates for single and 
return tickets, and the Anchor Line (Glasgow and New 
York) offer reasonable rates for single or return first- 
class tickets. A copy of a circular giving information in 
regard to Atlantic steamship rates will be sent to each 
member of the Association in a few weeks. It may be 
well to note that berths are to be applied for early in the 
season ; for the choice, if made late in June or July, may 
not be a large one. The Canadian Pacific and Grand 
Trunk Railway Companies have decided that round 
