An economical method of evaporation must be found.
The system is economical in fuel, but needs skilled attendance to keep the appliances and fittings in order.
The electrolytic parting of gold and silver has been shown to be more economical and free from the objections - such as the poisonous fumes - of the sulphuric acid process.
He visited all parts of the country himself, and personally encouraged agriculture; he introduced a more economical mode of mining and smelting silver; he favoured the importation of finer breeds of sheep and cattle; and he brought foreign weavers from abroad to teach the Saxons.
It is more economical Lowerin g to save the men's strength, however, by raising men.