Even the minor virtue of economy has been greatly promoted by the results of scientific research. New {151} scientific truth has through inventions taught us how to obtain greater effects with less expenditure of space, of time, of materials, and forces. It has enabled us to effect our objects quicker and with a diminution of waste. In the sugar manufacture for example, by means of the centrifugal machine, the sugar is deprived as perfectly of molasses in three minutes, as it was previously in three days, and the necessary manufacturing apparatus has been so much reduced in magnitude as not to require more than one half the space. The process of bleaching linen, which formerly required weeks, has by the discovery of chlorine been reduced to hours. Journeys which at one time occupied weeks now only require days. Messages are now transmitted in hours which formerly required months. Multitudes of instances might be adduced of the diminished cost of the comforts and conveniences of life, resulting in consequence of discovery of new scientific knowledge. Ultramarine for example, which at one time cost from ten to twenty pounds an ounce, has by means of chemical research been reduced in price to a few pence per pound; phosphorus, which formerly cost several guineas an ounce, now costs only as many pence. Numerous substances which were formerly thrown away, destroyed, or neglected, are now utilized. Coal tar and gas-water, which were at one time waste products in the making of gas, and which when thrown away were the causes of costly litigation to gas-companies, by polluting streams and wells, &c., {152} are now sources of very large income to those companies. Those substances yield great quantities of salts of ammonia, the beautiful aniline dyes, paraffin, benzene, napthaline, alizarine, and other valuable products. Glycerine also, which formerly was a most offensive waste product in soap-making, is now purified and used, to an extent of twenty millions of pounds annually, for a great number of purposes; as an emollient for the skin; as a source of nitro-glycerine and dynamite, used in blasting rocks, in warfare, &c. The immense beds of native sulphide of iron also, notably those of Tharsis and Rio Tinto in Spain, and of many other places, are now utilized, literally in millions of tons, for the production of sulphur, copper, oxide of iron, &c. A long list of instances of this class might be adduced if it were necessary, some of them of very great importance.[19] The promotion of morality by enabling us to detect crime, is one of the smaller influences of scientific research, and may be referred to as a set-off against the bad uses sometimes made of scientific knowledge. The telegraph is very commonly employed to assist in tracking and capturing criminals. Photography is also largely used in our gaols as a means of recognising offenders.