YELLOW SOAP, ROSIN SOAP or BAR SOAP owes its color to the large quantity of rosin incorporated. Most laundry soaps contain this ingredient, as it supplies the lather lacking in the tallow, their chief component. It also possesses detergent prop erties and is at the same time a cheap filling material. Another characteristic ingre dient is Sodium Silicate, but an excessive percentage of this offers no advantage except the reduction of cost to the manufacturer.
It is helpful advice to suggest to a housewife the purchase of laundry soap by the box, as it will be found less wasteful if allowed to harden for a moderate length of time. It is best cut in square pieces and stored on an upper shelf, with spaces of an inch or so separating the blocks.
Among other special types are AMMONIATED SOAP, used both for the laundry and bath ; BORAX SOAP, a hard white variety possessing remarkable detergent qualities ; NAPHTHA SOAP, and COLD WATER SOAPS—the last-named so prepared as to lather freely in cold water and therefore popular in many households for laundry purposes during hot weather.