Flash Powder for the Taking of Photographs by Artificial Light.
Year: 1898

page_text: Date of Application, 14th Jan., 1898-Accepted, 26th Feb., 1898
COMPLETE SPECIFICATION.
Flash Powder for the Taking of Photographs by Artificial Light.
I, AUGUST WEISS, of Meisengasse, 3, Strassburg, Alsace, Germany, Photographer,
do hereby declare the nature of this invention and in what manner the same is
to be performed to be particularly described and ascertained in and by the follow-
ing statement:-
The object of the present invention is a flash powder for the taking of photo-
graphs by artificial light which does not fire when rubbed or struck, but ignites
only at a high temperature, fulminates instaneously and produces a very bright
and most effective photographic light of considerable actinic power.
The flash powders hitherto used for photographic purposes are mixtures of
magnesium or aluminium.
Magnesium powders when ignited produce rays which are neither so bright nor
of such actinic power as mixtures of aluminium, so that the latter are preferable
as regards the action of the light.
Nevertheless it has not been possible hitherto to produce mixtures of aluminium
which also fully effect their object as to rapidity of combustion.
Moreover, all hitherto known aluminium powders are extremely dangerous
to handle, being caused to ignite by the least friction or the slightest concussion
and throwing out during the combustion igniferous sparks in all directions.
In consequence of these important drawbacks, aluminium powders in spite of
their great actinic power have not been adopted and their practical applicability
in connection with photography has been definitively denied by authorities on
the subject.
The mixture of aluminium which forms the object of the present invention
proves the contrary and does not present these disadvantages. It is free from
the drawbacks mentioned as it will not ignite even if struck sharply with a
hammer, but only at a high temperature, for instance by means of the explosive
substance of a lucifer match subjected to friction, but then ignites surely and
quickly and fulminates instantaneously.
By means of the present invention, accordingly the great actinic power of the
aluminium light becomes applicable to the fullest extent for photographic pur-
poses, and under the most favourable circumstances, in opposition to the adverse
opinions of photographic experts; and herein lies the new technical effect of the
present invention.
This effect is produced by the hitherto unknown mixture of powdered aluminium
(aluminium pulvis) and powdered perchlorate of potassium (kalium perchlorat
pulvis). The mixture is made in the usual manner, whilst the proportions of
the constituents of the mixture differ considerably and are to be measured always
according to the purpose in each particular case, that is to say, the proportions
depend upon whether a moderately quick, quick, or very quick combustion is
to be effected and the production of smoke more or less prevented.
Experiments made with this object have shown that as well mixtures of 85 parts
of perchlorate of potassium with 15 parts of aluminium as such of 40 parts of
perchlorate of potassium with 60 parts of aluminium give still useful results,

page_text: so that all mixtures lying between these limits from 85 to 40 parts of perchlorate
of potassium with corresponding parts (from 15 to 60) of aluminium respectively
may be regarded generally as suitable for photographic purposes.
A suitable mixture which gives average effects in relation both to quickness
of combustion and quantity of smoke resulting is one, for instance, composed of
60 parts of perchlorate of potassium to 40 parts of aluminium.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed I declare that what
I claim is:-
Flash powder for the taking of photographs by artificial light consisting of a
mixture of powdered aluminium (aluminium pulvis) and powdered perchlorate
of potassium (kalium perchlorat pulvis), in which the proportions of the con-
stituents of the mixture depend upon the intended degree of quickness of the
combustion and the prevention of smoke.
Dated this 14th day of January
H. GARDNER,
- Patent Agent, 166, Fleet Street, London,
Agent for the said August Weiss.