Improvements in Centrifugal Apparatus for Testing Relative Volumes of Mixtures of Liquids of Different Specific Gravities.
Year: 1891

page_text: Date of Application, 20th June, 1891-Accepted, 15th Aug., 1891
COMPLETE SPECIFICATION.
Improvements in Centrifugal Apparatus for Testing Relative
Volumes of Mixtures of Liquids of Different Specific Gravities.
I, JOHN LAIDLAW of the firm of Watson Laidlaw and Company of 98 Dundas
Street, Kingston, Glasgow, in the Counties of Lanark and Renfrew, North
Britain, Engineers 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 :-
My invention relates to improvements in apparatus for testing by centrifugal
action the relative volumes of liquids or substances having different specific gravities
and which are for the time being in a state of mechanical mixture. Similar
apparatus is at present in use for testing the amount of cream contained in a given
sample of milk or for testing the relative volumes of fat and other substances con-
tained in butter and the like. The samples to be tested are put into small glass
bottles which are placed on their sides radially and with their bottoms outwards in
receptacles in a disc which is caused to revolve rapidly. In the case of milk the
heavier portion known as skim milk is caused by centrifugal action to go outwards
to the bottom of the bottle while the cream or lighter portion of the milk floats
inwards towards the centre. Owing to the high velocity required to completely
separate the milk from the cream great outward pressure is exerted on the bottles
and they are very liable to burst. In fact it is found in practice that the bottles
will not stand as high a speed as is sometimes desirable.
The object of my invention is to get over this difficulty and to provide a machine
which will allow of the disc being revolved at any speed desired with less liability
of the bottles being broken.
In carrying out my invention I provide near the centre of the revolving disc a
receptacle for water or other liquid of suitable density. When the disc commences
to revolve the water or other liquid is driven into the receptacles or pockets con-
taining the glass bottles and completely surrounds the bottles. Thus there is
liquid inside and outside the bottles and the pressure due to centrifugal action set
up in the liquid contained in the bottles and in the liquid surrounding the bottles,
will be thereby equalized so that the liability of the bottles bursting will be greatly
reduced however high the speed may be.
In order that my invention may be properly understood and readily carried
into effect, I have hereunto appended one explanatory sheet of drawings in the
several figures of which corresponding parts are marked with the same letters of
reference.
Figure 1 is a plan of half of the revolving disc.
Figure 2 is a vertical section of the disc while at rest.
Figure 3 is a vertical section of part of the disc when revolving rapidly.
The disc marked A has a number of pockets B3 formed in it for holding the
testing bottles C, and is supported on a central spindle D which is driven by any
convenient mechanism. Near the centre of the disc and surrounding the spindle
there is a circular trough E which is filled with water or other suitable liquid as
shewn at Figure 2 when the disc is at rest. The test bottles are filled with the liquid
or other substance to be tested and placed in the pockets and the disc is made to
revolve rapidly. The centrifugal action will cause the liquid in the trough E to
How into the pockets as shewn at Figure 3 and the bottles will thus become
surrounded so that there will be nearly the same fluid pressure outside and inside
he test bottles. A lip b, is formed projecting beyond the pockets which causes
he liquid contained in the trough to enter the pockets and ensures a proper and
sufficient level of liquid surrounding the test bottles being maintained when the

page_text: disc is being revolved at a high speed. When testing other liquids or substances
having a different specific gravity from water, a liquid of similar density to that of
the substance or liquid to be tested can be employed for surrounding the bottles in
order that the external and internal pressures may be equalized.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:
:-
1. In a centrifugal testing machine the method of preventing the tendency of
the testing bottles being burst by the pressure of the substance or liquid contained
in the testing bottle due to centrifugal action, which consists in causing the bottles
when set in motion to be surrounded with water or other liquid of suitable density
so as to have as nearly as possible the same fluid pressure outside and inside the
testing bottles, substantially as described and illustrated in the accompanying sheet
of drawings.
2. In a centrifugal testing machine the disc with pockets or their equivalent for
carrying the testing bottles having a circular trough formed in it for holding
liquid which by centrifugal action is caused to flow over the lip or outer edge
of the trough into the pockets, and surround the bottles as and for the purpose:
described.
3. In a centrifugal testing machine the disc with pockets or their equivalent
having a lip formed on the upper surface in order to cause the liquid contained in
the trough surrounding the central spindle to enter the pockets containing the test
bottles, and also that a proper and sufficient level of liquid surrounding the test
bottles may be maintained when the disc is being revolved at a high speed, as and
for the purpose described.
Dated this 19th day of June 1891.
BOTTOMLEY & LIDDLE,
154, St. Vincent Street, Glasgow, Applicant's Agents.