DETECTIVE RAY.

Star (Christchurch), Volume LXVI, Issue 20542, 18 February 1935, Page 5

DETECTIVE RAY.

Knows an Egg’s Age by Looking at It. STUDY IN INFANCY. LONDON, January 11. The scientific detective—with an eye more penetrating than any of the celebrated detectives of fiction —has arrived. This is the ultra-violet ray, known to most people solely for its great curative powers. Its scope of detection is so wide that it is becoming of great service, not only in certain classes of crime detection, but also to people so differently occupied as Customs officers, analysis, museum curators and stamp collectors. It has been discovered that the ray has a marvellous range of service, and all over the world scientists are experimenting with its ever-increasing tises as a detector. “ This study is as yet only in its infancy,” said Dr Julius Grant, a wellknown analyst, who has made a special study of the subject. “We who are experimenting with it are constantly adding to our store of knowledge of its possibilities.”

Exposing Forgeries. Various branches of crime will be made more difficult because of the growing uses to which this knowledge is being put. Dr Grant explained that the ray is already utilised in legal and police work for the detection of forgery on documents by alterations and erasures. What appears perfectly normal to the | naked eye is frequently ruthlessly «x- , posed by this penettrative ray. In the same way secret inks have been made to give up their secrets, and deletions on documents have been made so discernible that in some cases the actual words, which have been scraped out or obliterated by chemicals have become

clearly visible when subjected to the rays of the lamp. In conection with foodstuff frauds the ray has many uses. It can, in many cases, detect the adulteration of food, such as butter, coffee, milk and flour, merely by revealing a colour foreign to the normal article. As an illustration, milk subjected to the rays develops a canary-yellow colour, but if even a trace of sodium salicylate has been added the colour changes to a bluish white. Eggs cannot conceal their age from this detective. According to Dr Grant, the serum or white of the egg changes its colour by minute degrees as the egg grows older, and while the change is invisible to the naked eye, it cannot escape the ultra-violet ray. The ray is also able to tell if the marks of origin of imported eggs have been obliterated, by making the erasure visible again. Recent experiments have also disclosed a new sphere of activity for this scientific detective. It has been discovered that under the rays the microscope can reveal cultures in organisms which were unknown to students using the ordinary white light. “ And these things are only a beginning,” Dr Grant declared.