Carob (ceratonia siliqua) seeds are known to have remarkable
uniformity of weight, so remarkable that they were used several
millenia ago as a natural weight standard. I have an idea what weight
they are, but want to see something based on physical measurements.

Preferred method:
Grocer with electronic scale might be good source. Take 100 carob
seeds (less than 1 kilogram, I think), measure individual weights and
state the range of weights and the average in "x.xx gram" format. Then
randomly divide the 100 into five groups of 20 carob seeds each, and
report the total weight of each group of 20 seeds in "xx.xx gram"
format.

Thank you

migrantlabourer-ga,

This is certainly one of the odder questions that I have tackled!
Fortunately, I had a contact in the gardening business who allowed me
to borrow a large quantity of carob seeds.

For your reference, these seeds have been removed from the pods for a
long time, and thus, quite dry.

Procedure
---------
1. Removed any seeds that were cracked or clearly chipped (since they
do not reflect the true average value of Carob seeds).
2. Tared the balance.
3. Placed each seed on the balance and allowed 2-5 seconds to stabilize.
4. Repeated step three for 150 seeds.

Balance Specifications
----------------------
Name:               Mettler AJ100 Balance
Range:              0 - 110 g 
Readability:        0.1 mg 
Reproducibility:    0.15 mg 
Accuracy:           ± 0.2 mg 
Stabilization Time: 4 sec 

Analysis
--------
http://www.maxlin.ca/tos/ga/carobweight.xls

Results
-------
Average Mass:       208.8 mg
Standard Deviation: 2.6 mg
Minimum Value:      201.7 mg
Maximum Value:      216.7 mg

Comments
--------
While the range of seed weights may seem very large, 16 mg is in
actuality extremely small.  With a standard deviation of 2.6 mg (~1%
of the seed's weight) it is easy to see why they were used for
accuracy. These experimental values also correspond with the
historical weight of carob seeds (typically 3-4 grains which is
equivalent to 194-260 mg)


Cheers,
tox-ga

---

Clarification of Answer by tox-ga on 02 Feb 2005 00:11 PST

migrantlabourer-ga,

The weights for the random groupings of 20 seeds can be found on sheet
two. They had the following statistics:

Mean:               4.179 g
Std Dev:            0.015 g
Min Value:          4.159 g
Max Value:          4.201 g

These values, at least to me, were surprisingly accurate.

In case you do not have Excel, I have also uploaded a text version of
the data which can be found at:
http://www.maxlin.ca/tos/ga/carobweight.txt


Cheers,
tox-ga