Improvements in Refractometers for Liquids.
Year: 1899

page_text: Date of Application, 3rd May, 1899
Complete Specification. Left, 23rd Jan., 1900-Accepted, 24th Mar., 1900
Improvements in Refractometers for Liquids.
.
CARL PULFRICH, Doctor of Philosophy,' of Carl-Zeiss-Strasse, Jena, Grand-
Duchy of Saxe-Weimar, Germany, do hereby declare the nature of this inven-
tion' to be as follows:-
:
L
اران :
41.
"
The invention relates to refractometers for. liquids and particularly to the
so-called Abbe refractometers, which are founded on the observation of the
critical or limit angle, of total reflection and a special type of which, has been
described in the Patent to Abbe and Zeiss No. 22751, 1892. In these instru-
ments a thin layer of that liquid of which the refractive power is to be deter-
mined, is embedded between two. glass prisms arranged before the objective of
a telescope.
JAM
.
According to the present, invention for certain. technical purposes, where com-
paratively large quantities of the liquid may be disposed of, for instance for
determining the percentage.. of alcohol contained in an alcoholic solu-
tion or
the degree of concentration of a solution of salt etc. from
.
the refractive power of these.. liquids, the second (outer) glass prism
effecting the entrance of light into the layer of liquid is wholly dispensed
with: Thereby not only a cheaper and less complex. instrument-is- created, but
the manner, of measuring is also considerably. simplified,, because for examining
a liquid, by, means of a refractometer, the end-surface of which is to be brought
in contact with the liquid, the prism end of this instrument is simply to be
dipped into the said liquid.. It will be, understood, that in doing so care must
be taken that light is allowed. to meet with the prism in the same grazing"
direction as formerly by the intervenience of the-second or covering prism.
It is evident, that with a "dipping refractometer" the refractive power of a
liquid may be determined in the same simple manner as its temperature by
means of a thermometer or.its specific weight by means of an areometer..
001
Improvements in Refractometers for Liquids:
I, CARL PULFRICH, Doctor of Philosophy, of "Carl-Zeiss-Strasse, Jena, Grand-
Duchy of Saxe-Weimar, Germany, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed; to be- particularly de-
scribed and ascertained in and by the following statement:-
The invention relates to refractometers for liquids and particularly to the
so-called Abbe refractometers, which are founded on the observation of the
.

page_text: critical or limit angle of total reflection and a special type of which has been
described in the Patent to Abbe and Zeiss No. 22751, A.D. 1892. In these instru-
ments a thin layer of that liquid of which the refractive power is to be deter-
mined, is embedded between two glass prisms arranged before the objective of
a telescope.
According to the present invention for certain technical purposes, where com-
paratively large quantities of the liquid may be disposed of, for instance for
determining the percentage of alcohol contained in an alcoholic solu-
tion or the degree of concentration of a solution of salt etc. from
the refractive power of these liquids, the second (outer) glass prism
effecting the entrance of light into the layer of liquid is wholly dispensed
with. Thereby not only a cheaper and less complex instrument is created, but
the manner of measuring is also considerably simplified, because for examining
a liquid by means of a refractometer, the end-surface of which is to be brought
in contact with the liquid, the prism end of this instrument is simply to be
dipped into the said liquid. It will be understood, that in doing so care must
be taken that light is allowed to meet with the prism in the same grazing'
direction as formerly by the intervenience of the second or covering prism.
"
It is evident that with a "dipping refractometer" the refractive power of a
liquid may be determined in the same simple manner. as its temperature by
means of a thermometer or its specific weight by means of an areometer.
In the annexed drawing:
Fig. 1 shows the improved refractometer while being dipped in an inclined
position into the liquid contained in a vessel, which is translucent at one side.
Fig. 2 shows the same instrument in an upright position, the vessel having a
translucent bottom and being illuminated from below.
The vessel a intended for the reception of the liquid should be provided with
a window b preferably of ground glass either at one side as shown in Fig. 1 or
at the bottom as shown in Fig. 2. Mirrors c may facilitate illumination.
According to the arrangement of the source of light and of the mirror and the
window the instrument d is to be held either more or less oblique (Fig. 1) or
perpendicularly (Fig. 2) so as to enable the light to graze the refracting surface
of the prism e, that is to say to impinge upon this surface at an angle of incidence
most approximate to 90°.
In the examples shown the prism is supposed to be rigidly connected with the
telescope as usual in one type of Abbe refractometers for liquids. But it will be
understood that the invention-as it only relates to the prismatic end of the
instrument is also applicable to that other kind of Abbe refractometers for
liquids, in which, for being enabled to test liquids of any degree of refraction, the
telescope is to be rotated relatively to the prismatic device.
The
The vessel may either be open as in the examples shown or provided with such
arrangements as will allow to bring it into firm connection with the immersed
refractometer and at the same time shut off its contents from the outer air.
instrument fitted in the latter way with the filled vessel may be illuminated by
turning it towards the bright sky or, if at the same time a certain temperature is
to be obtained, by dipping it into a larger vessel filled with water and constructed
like the vessels in Fig. 1 and 2.
If a series of samples of liquids of the same kind is to be examined, it will be.
convenient to fill the samples into ordinary bowl-glasses and to put these glasses
into a large vessel having similar illuminating devices as the vessels in Fig. 1
and 2 and preferably filled with water which serves for the regulation of the
temperature as in the above case.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:-
In a refractometer for liquids the combination with a telescope of a prism

page_text: arranged before the objective of the telescope so that of its two refracting sur-
faces the more oblique one is the front surface of the total instrument, sub-
stantially as and for the purpose set forth.
Dated this 20th
JT
1000