Making a set of weights
Without a set of weights, an equal arm balance can be used to
see whether various objects are equal in weight or not. This is done in Activity
I-6* where the equal arm balance shows that if one of the cubes is cut into
several pieces, the pieces still weigh the same as the other cube that was not
cut.
(* Peace Corps ICE Manual M10, Preserving Food by Drying, p.51)
If the objects are to be weighed with the equal arm balance, a
set of weights is needed. This is necessary where the weight of a piece of fresh
food is to be compared with the weight of the same piece of food after it has
been dried. The equal arm balance can be used for weighing by putting the piece
of food on one side of the balance and by putting enough weights on the other
side to balance the food.
The set of weights should be based on some easily available
objects that all weigh about the same. In Section S. things like staples, common
pins, and paper clips are suggested for testing the sensitivity of the balance.
However, these a-e too light to be useful for weighing the food pieces. They
also have the disadvantage that unless they are all bought from the same source,
they may not all have the same weight. Washers also do not make suitable
weights, because they are made from scrap pieces of sheet metal, and although
the diameter may be the same, the thickness varies tremendously.
Bottletops from Coca-Cola, Fanta and beer bottles are quite
uniform in weight. These are probably the best things on which to base your set
of weights. They have the added advantage of being obtainable for free.
The set of weights can consist only of bottletops. For example,
a piece of food might weigh 130 bottletops fresh and 47 bottle-tops after being
dried. This gets to be a lot of bottletops to pile on the balance, however.
Somewhat heavier objects that are quite uniform are batteries of
the kind used in flashlights and radios. The weights may vary between batteries
from different makers, but all batteries of a certain type made by the same
company should weigh about the same. Consider that you have some small batteries
that each weigh 14 bottletops, and some large batteries that each weigh 55
bottletops. To weigh the fresh food in the example, two large batteries would
equal 110 bottletops, one small battery would add 14, and 6 bottletops would add
the rest, to reach the total of 130 bottletops of weight. To weigh the dried
fruit, three small batteries would equal 42 bottletops, and 5 bottletops would
be added to balance the food's weight of 47 bottletops.
Objects such as these can be used to make sets of weights
suitable for all the food drying activities in this book.
