AMONG THE MANUFACTURERS

AMONG THE MANUFACTURERS

R. U. V. Water Purification Apparatus.

White sunlight when broken up by a prism into its component parts will show the rainbow colors. A study of the spectrum shows that each color has a vibration wave of a different length, being longest at the red end, and reducing to the minimum at the violent end. By using certain apparatus it is found that vibrations with very short wave lengths lie beyond the violet of the spectrum. These rays are invisible to the eye because the wave lengths are too short to effect the optic nerve. They are called ultra-violet rays. Ultra-violet rays have a decided effect on certain chemicals, often being called chemical rays for this reason. Water, air and clear rock quartz crystal transmit the rays to about an equal degree. Ordinary glass as well as all material opaque to sunlight are opaque to ultraviolet. Ultra-violet rays are found in sunlight and are also produced by the electric spark or arc. The commercial type of lamp consists of a clear quartz receptacle, mercury for the formation of the arc and the necessary seal to maintain a vacuum in the receptacle. That the receptacle be made of quartz is obviously necessary to allow the rays produced by the mercury arc to pass into the surrounding air or water. Ultra-violet rays kill both bacteria and spores as has been proven beyond doubt by many experiments on sunlight and electrically produced rays. The actual reason why ultra-violet rays kill bacteria is not known, although several wellfounded theories have been advanced. It may be stated here that dead bacteria are of the same composition as ordinary foodstuff. and also should a thousand be pressed in a single drop of water, they are so minute that its clarity would not be effected in the least, nor could their presence be detected in all probability by chemical analysis. On this principal the R. U. V. Company, Incorporated, of 50 Broad street, New York City, have devised an apparatus for the purification of water. It has been determined, however, that bacteria are not killed in R. U. V. apparatus by any oxidizing chemical which is generated from the water by the act of the rays. Professor Henri proved this when he ran a tenhour test on a single tank of water and found the formation of only 1/400 of the amount of chemical that would be required for sterilization. The period of illumination in commercial apparatus is rarely as long as one minute. It has been further proved that sterilization by ultra-violet rays takes place without any measurable change in the natura1 temperature, taste, odor, chemical property of gas content of the water. There are two variables found in ultraviolet rays water sterilization. The first, the voltage on which the lamp operates (the voltage determines the ultraviolet power of the burner); second distance of the bacteria from the lamp, the time required to kill bacteria of any set type varies approximately inversely as the square of distance from the burner, that is, the further the organism is from the lamp the longer the time it takes to kill it. Tt will be noted that it is stated any set type of bacteria. This is done because different types of bacteria have different resisting powers against the sterilizing agent, while spores arc still somewhat more resistant than bacteria. The fact is true whether the sterilizing agent be heat, chemicals or ultra-violet, that the variation is less with the ultra-violet than with the others. The illustration herewith shows one type of R. U. V. apparatus with a capacity of 1,000 gallons per hour. The operation of this apparatus is simp_____e. To start the sterilizer, it is only necessary to heat the mercury vapor burner, and then turn on the water; once started the lamp will burn on indefinitely if desired. In some of the smaller types of sterilizers, even the tilting of the burner is done automatically. The R. U. V. Company has issued a series of bulletins descriptive of their process. These bulletins are both instructive and interesting.