Improvements in Assay or Chemical Balances.
Year: 1892

page_text: COMPLETE SPECIFICATION.
Improvements in Assay or Chemical Balances.
I, CONRAD FRIEDRICH BETTING, of Wehlheiden, near Cassel, in the Empire
of Germany, Mechanical Instrument Maker, 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 assay or chemical balances and comprises mechanism
whereby the weights can be applied to and removed from the balance without
opening the case enclosing the same, such mechanism consisting essentially of a
series of levers adapted to carry the weights and to deposit them upon the pans as
required through the medium of cams operated by heads or knobs placed outside
the case.
In order to enable my invention to be fully understood I will describe how
it can be carried into practice by reference to the accompanying drawings, in
which :-
Figure 1 is a front elevation of an assay or chemical balance constructed
according to my invention:
Figure 2 is a similar view of the weight receiving part of the balance and of
the mechanism for depositing the weights thereon:
Figure 3 is a sectional plan; and,
Figure 4 is a perspective view of the upper part of the same:
Figure 5 is a perspective view of one of the lower weight carrying levers with
its weight:
Figure 6 is a plan of the same :
Figure 7 is a perspective view of the upper part of the weight receiving portion
of the balance:
Figures 8 and 9 are views of the larger and smaller weights respectively.
Figure 2 is drawn to a larger scale than Figure 1; and Figures 3 to 9 are
drawn to a still larger scale.
Similar letters in all the figures indicate similar parts.
a, Figure 1, is the glazed case enclosing the balance and the mechanism for
applying the weights thereto. This mechanism comprises a frame b secured to
the case a by screws passing through holes c, c, Figures 5 and 6, and consisting
of four standards d, d, e, e, a base-plate f and a rectangular upper portion g. In a
balance to weigh up to 200 grammes as illustrated in the drawings the front
standards d, d are provided with 9 holes, and the rectangular upper part g with 8 holes,
which are placed at regular distances from each other. In these holes are fitted
spindles carrying discs i having cutaway portions by means of which, in con-
junction with stop-pins j, the rotary movement of the spindles his limited. On the
spindles h are fixed cams k designed to lift the levers 7 and m when the spindles h
are turned to the right, and to lower them when the spindles are turned to the left.
The levers m work on centres n, n between the standards e, e and the levers / are
mounted in rows of four upon two screw-threaded spindles n. The levers m
are forked at the ends opposite their pivotting points and are provided with side
flanges or ledges p, p, Figures 5 and 6, between which the weights q, Figure 8, are
made to loosely fit. To prevent the weights y from shifting in the direction of the
length of the levers m the flanges p of the forks are made with semi-circular
concavities r to fit the necks of studs s upon the weights. The weights g from
one gramme upwards are of a flat rectangular form and the heavier they are the
onger and broader they are made.
The free ends of the levers
are constructed in the form of hook-shaped

page_text: forks t. For the sake of clearness only the upper row of levers with their hook-
shaped forks t is shewn in Figure 4, the lower row shewn in Figure 2 being
arranged in precisely the same way as the upper row.
Weights g of fractions of a gramme, which are applied and removed by means
of the hook-shaped levers 7, are made of wire of the shape shewn in Figure 9.
The weight receiving part of the balance consists of a pyramid-shaped frame u
to which are fixed pans upon which the weights are laid by the mechanism
hereinhefore described. The pans are provided with ledges w between which
the weights are held so that they cannot be displaced to the right or to the left
hand. Between the inner edges of the forks and the outer edges of the pans va
sufficient space is left in order that when the weights 7 are lifted off or laid on by
the levers m contact of the latter with the pans is prevented. The arrangement
of the pans upon the pyramidal frame u is such that the largest pan for the greatest
weight (100 grammes in the present case) is secured at the bottom. Then follow
in ascending order the pans for 50, 20, 10, 10, 5, 2, 1 and 1 gramme. The forks
of the levers m diminish in size upwards to an extent corresponding to the size
of the weights. Two carriers x and y secured to a vertical bar above the
pyramidal-frame u serve to receive the weights 71 of fractions of a gramme.
Each carrier is provided with four pairs of hooks a¹. The weight receiving portion
of the balance is suspended from the beam in the usual way, but so that there can
be no rotation round the vertical axis. At the lower part of the pyramid of pans
is placed a pin 1 which fits into a conical depression in a support c¹ when the
balance is not being used and is held there, thus preventing the pyramid of pans
from oscillating and also causing it to remain constantly in the vertical line of the
terminal knife edge.
The spindles h extend outside the case a where they are fitted with heads d'
for the purpose of turning the spindles and thereby operating the cams k.
The lowest portion of the hooks a' of the carriers and y corresponds with the
lowest point in the hooks of the levers 7. The pairs of hooks t of the levers 7,
when the latter are turned on their spindles, pass outside the pairs of hooks a¹
of the hooked carriers x and y, as clearly seen in Figure 3, and can thus lift the
wire weights q' from the latter when the levers are raised by the cams k. Figure 7
shews clearly how the wire weights are held in the double hooks of the hooked
carrier. Any shifting of the weights is prevented by their peculiar shape. In
a similar manner the concavities of the levers m when the latter are moved
on their centres come opposite the middle of the front and back edges of the
pans v, so that the weights are safely lifted from the pans when the levers are
raised and are set down again in the same position on the pans when the levers
are lowered.
The movements of the levers are strictly limited so that a weight when lifted
by one lever cannot come into contact with the weight lying upon another-lever
situated above it, as illustrated in Figure 2. The spaces intervening between the
pans and the weights when lifted from them are sufficiently large to prevent
the pan, when swinging, from touching either the lever or the weight.
To make use of a balance of this construction the object or substance to be
weighed is laid upon the pan e¹, Figure 1, usually provided for this purpose and
the case is then closed.
Suppose the weights to be all lying upon the levers and m, the spindle-heads d'
all turned to the right and the levers lifted by the cams k. A weight approximately
corresponding to that of the object or substance is laid by way of trial in its
pan by turning the head d' upon which the value of the weight required is
engraved to the left as far as the stop j will allow. If the swing of the balance
shews the weight selected to be too heavy, the action of the balance must be
stopped and the head d¹ which was previously turned to the left is now turned to
the right, whereby the weight is raised, and in the same manner as before the next
lower weight is laid upon its pan v. If this one be too light the weight which

page_text: lies above it is added. If the latter is still insufficient the next lower one is added
and so on until the balance is brought into exact equilibrium. The milligramme
and its fractions are determined by riding weights, not shewn, upon the beam f'
of the balance, which weights are shifted by means of the hook g¹ on the sliding-
bar h' operated by a knob ¹ outside the case a. Since only the heads d have to
be moved in order to lay on and take off the weights, the weighing can be con-
veniently and rapidly effected. The smallest weight used is 0.01 of a gramme.
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 an assay or chemical balance mechanism whereby the weights can be
applied to and removed from the balance without opening the case enclosing the
same, such mechanism consisting essentially of a series of levers adapted to carry
the weights and to deposit them upon the pans as required through the medium
of cams operated by knobs or heads placed outside the case, substantially as
hereinbefore described.
2. In an assay or chemical balance, the combination with the suspended pyramid
of weight receiving pans v and the hooks a', of the levers and m, cams k, spindles h
and heads d' thereof placed outside the case a, substantially as and for the purpose
set forth.
3. The improved assay or chemical balance herein before described and illustrated
in the accompanying drawings.
e 3rd day of February 1892.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.