Year: 1887

page_text: Date of Application, 2nd Nov., 1887
Complete Specification Left, 14th July, 1888
Complete Specification Accepted, 17th Aug.. 1888
I, CONSTANTIN FAHLBERG, doctor of philosophy, one of the firm of Fahlberg,
List & Co., and residing at Selbke-Westerhüsen in the Kingdom of Prussia, do
hereby declare the nature of this invention to be as follows:-
The process of producing phosphorus trichloride, which consists in causing gaseous
chlorine to act on phosphorus, has heretofore always been carried out in vessels of
glass or earthenware, metallic vessels having been avoided on account of the corrosive
action of chlorine on metals. The said glass or earthenware vessels, however, do not
allow of producing the phosphorus trichloride otherwise than in small quantities, and
their fragility is a constant source of danger. Besides, as it is unsafe to charge the
said vessels with yellow phosphorus, red or amorphous phosphorus has only been
used, whereby the cost of the product is considerably increased.
My invention has for its object to produce phosphorus trichloride in metallic vessels
and from yellow phosphorus without being exposed to the aforesaid inconveniences,
and it is based on the discovery which we have made, that metals are not attacked by
chlorine when phosphorus is present in excess.
I carry out my invention by means of an apparatus consisting in a retort made of
metal and having preferably the form of a horizontal cylinder, the said retort being
surrounded by a steam-jacket and connected at one end to the supply-pipe for dry
chlorine gas, at the other end to a refrigerator in which the vapours of phosphorus
trichloride are condensed, and at the top to a vessel from which yellow phosphorus is
supplied in liquid state. The latter vessel is provided with a steam heating-coil for
melting the phosphorus, and at its bottom there is a valve, fitted with means for

page_text: adjusting the same, and whereby the flow of phosphorus to the retort is regulated.
Into the retort is inserted a tube for the introduction of a thermometer, and at either
end of the same or on the pipes connected therewith are arranged sight-glasses.
According to the indications of the thermometer and the colour of the contents of
the retort visible through the sight-glasses, the supply of steam to the steam-jacket
and the admission of chlorine and phosphorus to the retort are so regulated that the
proper temperature and the required excess of phosphorus over the chlorine is
maintained throughout the process.

page_text: COMPLETE SPECIFICATION.
Improvements in Apparatuses for the Production of Phosphorus
Trichloride.
I, CONSTANTIN FAHLBERG, doctor of philosophy, one of the firm of Fahlberg,
List & Co., and residing at Selbke-Westerhüsen in the kingdom of Prussia, 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 following
statement:-
The process of producing phosphorus trichloride, which consists in causing gaseous
chlorine to act on phosphorus, has heretofore always been carried out in vessels of
glass or earthenware, metallic vessels having been avoided on account of the corrosive
action of chlorine on metals. The said glass or earthenware vessels, however, do not
allow of producing the phosphorus trichloride otherwise than in small quantities, and
their fragility is a constant source of danger. Besides, as it is unsafe to charge the
said vessels with yellow phosphorus, red or amorphous phosphorus has only been used,
whereby the cost of the product is considerably increased.
My invention has for its object to produce phosphorus trichloride in metallic vessels
and from yellow phosphorus without being exposed to the aforesaid inconveniences,
and it is based on the discovery which I have made, that metals are not attacked by
chlorine when phosphorus is present in excess.
I carry out my invention by means of an apparatus consisting in a retort, made of
metal and having preferably the form of a horizontal cylinder, the said retort being
surrounded by a steam-jacket and connected at one end to the supply-pipe for dry
chlorine gas, at the other end to a refrigerator in which the vapours of phosphorus
trichloride are condensed, and at the top to a vessel from which yellow phosphorus is
supplied in liquid state. The latter vessel is provided with a steam heating-coil for
melting the phosphorus, and at its bottom there is a valve, fitted with means for
adjusting the same and whereby the flow of phosphorus to the retort is regulated.
Into the retort is inserted a thermometer, and at either end of the same or on the
pipes connected therewith are arranged sight-glasses.
On the annexed sheet of drawings this apparatus is shown by Fig. 1 in sectional
elevation, while Fig. 2 represents a part thereof in plan. A is the retort made of
metal, for instance of iron, copper, phosphorus-bronze or brass, and a the steam-jacket
surrounding the same, and which is supplied with steam by the pipe f, while the
water of condensation is discharged at g. s is the pipe through which the chlorine
gas is introduced into the retort, C the refrigerator connected to the retort by the
pipe n, and B the vessel from which the phosphorus is supplied. o is the steam-
heating-coil arranged within the latter, and the valve by which the flow of phosphorus
to the retort is controlled. the said valve being fitted with the regulating screw k.
and are two hinged lids for closing the vessel, t is the thermometer, c is a tube

page_text: serving to protect the same, and e el are the sight-glasses, which, in the apparatus
shown by the drawing, are inserted into the top of the tubular pieces d d', forming
portions of the respective pipes s and n, and one of which is shown in plan by Fig. 2.
The refrigerator is preferably made of cylindrical shape in view of facilitating the
cleaning of the same, and it is provided with a jacket through which water is caused
to flow, as in other like apparatuses of this kind. q is a siphon-pipe for the outflow
the product obtained, and a pipe for the issue of uncondensed vapours. The
vessel B and the refrigerator C may both be constructed of any suitable metal, but the
latter is with advantage coated with lead inside. The valve i is preferably made of
asbestos.
The mode of working with the apparatus is as follows. The vessel B is filled to
about one half with water and then charged with yellow phosphorus. Steam is there-
upon admitted to the coil o and the jacket a, and, after the phosphorus has been melted,
a portion thereof is allowed to run into the retort. Subsequently, the chlorine gas,
produced, purified and dried by any known means, is conducted into the same.
The
temperature within the retort, which rises from the action of the chlorine on the
phosphorus, is then regulated, according to the indications of the thermometer t, by
suitably checking or increasing the influx of the chlorine, and by shutting off the
steam from the steam jacket a, or turning it on, while the process is controlled in
respect to the admission of phosphorus according to the color of the vapours visible
through the sight-glasses e e', the said colors varying as there is an excess of phosphorus
or of chlorine present in the retort.
The phosphorus trichloride condensed in the refrigerator C, continuously flows off
through the pipe 7 and is collected in vessels of glass or earthenware.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to bo performed, I declare that what I
claim is :
1. In an apparatus for the production of phosphorus trichloride, the combination,
with each other, of a retort made of metal, a steam-jacket surrounding the same, a
vessel for melting phosphorus, a valve for controlling the flow of phosphorus from the
said vessel to the retort, a pipe for admitting chlorine to the retort, a refrigerator for
condensing the vapours of phosphorus trichloride produced, sight-glasses through
which the contents of the retort can be examined, and a thermometer inserted into the
retort, substantially as hereinbefore described.
2. In an apparatus for the production of phosphorus trichloride, the combination,
with each other, of the retort A made of metal, the steam jacket a, the vessel B
communicating with the top of the retort and provided with the steam-heating-coil o,
valve i and regulating-screw k, the chlorine suppl pipes, the refrigerator C connected
to the retort by the pipe n, sight-glasses e e and thermometer t, substantially as
specified.
Dated the Fourteenth day of June 1888.
CARL PIEPER,
Agent for Applicant.