tintin1689, on 09 March 2012 - 01:02 PM, said:
"Little drops of water,
Little grains of sand,
make the milkman wealthy
and the grocer grand."
Another comment from the period and earlier was to refer to milk having come from the "iron cow", meaning the farmyard water pump. As late as WW2 there were some milk producers still delivering milk by drawing it direct from a milk churn brought to the doorstep and pouring it into the householder's own jug, with suspicions that the churn had been diluted.
The "grains of sand" in the doggerel refer to the dilution of sugar at the time it was weighed out for each customer from a sack which might or might not have been adulterated. I know of know no specific case of that happening at a grocer's, but it certainly happened in the case of sugar bowls in a certain cafe in the 1920s.