THE X-RAY AS A CRIME DETECTOR.

Dunstan Times, Issue 3130, 14 August 1922, Page 7

THE X-RAY AS A CRIME DETECTOR.

(By Frederick A. Talbot.) During the past few years vast improvements have been made in radiographic science, with the result that X-rays are now being freely employed for the detection of malpractices andi criminal activities in every field, it is not always necessary to resort to photography unless a permanent record is desired, or it is proposed to confront the delinquent with convincing evidence of his guilt. Radio-photography is now a simple operation. The perfection of the tube —the source of illumination —the photographic emulsion, the screen, and the apparatus in general facilitates tins work. The photographic plate does not have to be removed from the black paper envelope in which it is packed owing to the rays readily penetrating this material, while the pictures can be taken in the thousandth part of a second. The work has been reduced to press-the-button simplicity, and the images thus obtained are striking for brilliancy, clarity and definition of the most minute detail. The rays have proved of incalculable value in the frustration of smuggling tactics. Their utility in this direction was emphasised during the European war. Rro-German interests in the United States of America resorted to many ingenious devices to hoodwink the British hawks maintaining the blockade and America’s scrupulous adherence to neutrality. Goods baled and consigned to ostensible neutral trading houses in Scandinavia, Holland, and Denmark were employed as the vehicles for contraband and the passage of compromising documentary information. Some of these bales were only loosely wrapped with brown paper and indifferently hooped by iron bands, the apparent carelessness in packing being intentional to disarm suspicion. The vigilant British authorities probed these subtleties, however, and at the same time quietly drew the notice of the American Government to the irregularities winch were being practised. Thereupon the American officials were equipped with X-ray apparatus to subject the consignments dispatched from dubious exporting houses to examination, this procedure was preferable to that of breaking open the packages, because it did not arouse any suspicions that the shipments wore being scrutinised and the movements of the shippers recorded. Upon discovery the guilty packages were set upon one side or went forward in such a manner as to ensure capture. The faking of paintings of ancient date and their passing off as the works of old masters has proved a highly lucrative occupation for many years. Renovation and alteration were completed so cleverly as to defeat minute examination by experts. In 1914 a German investigator, Faber, whose attention had been drawn to this traffic, conceived the idea of utilising the X-rays to detect such frauds. The war supervening, this line of research had to be abandoned. However, it has since been revived by a French enthusiast, Dr A. Cheron, and the results are interesting and probably inimical to the sustained prosperity of those indulging in the business. . , In this instance advantage,is taken of the difference between the bases of the colors and materials used by the old painters and these of to-day. Ihe former almost exclusively favored mineral colors, while contemporary artists rely upon lake colors, hj urthennoie, the old painters worked upon panels of wood or canvases treated with carbonate of lime, which is transparent to the rays, whereas modern artists employ canvases which are treated with white lead and which is opaque to the rays. Consequently, it is a very simple matter to determine whether an ancientlooking canvas is genuine or spurious by this means of investigation, and in such a. manner as leaves no room for doubt. The faker, to avoid being trapped. will have to resort to the color bases and materials favored by the artists of long ago. . Interesting attempts are also being made to employ the rays for the discovery of criminal alterations to cheques and bank notes, as well as to legal and commercial documents, but tins has proved to be a somewhat baffling quest. Nevertheless, persistent research has enabled the quest to be advanced to a decisive stage, and one which is likely to lead to further striking development. The defective goods were returned to the laboratory and scarchingly examined. They were found to carry foreign and low-grade material. This discovery cast an aspersion upon the chemical and testing staff, which was responsible for the acceptance of all raw material. The “Please explain!” not proving wholly satisfactory, drastic changes were made in the technical side of the organisation. Still tlie complaints rolled in, and investigation continued to reveal the recurring presence of the foreign materials. The directing forces, satisfied that the raw materials were up to standard and that the technical staff was efficiently discharging its duties, were forced to acknowledge that the trouble was occurring somewhere in the works, and at some period of the process of manufacture. The difficulty was to trap the criminal. At the conclave where the problem was discussed one of the technicians suggested the acquisition of an X-ray apparatus and the submission of the products to examination before dispatch. He explained how the operation could be speedily conducted, how the presence of the foreign material, from its constitution and different density, could be detected, and how, by the process of elimination, the crime might be narrowed down until the vat in. which the irregularity occurred could he found, when by further selection it would be possible to bring the offence home to the guilty party. The apparatus was installed and the final task of examination before dispatch was carried out by two or three of the technical staff without the employees being apprised of the fact. As the technical man had explained, the faulty products could be promptly detected, and wore found to be irregularly distributed, although arriving in batches. The directing forces then issued an order that the consignments from the various machines were to he kept separate, on the plausible pretext that certain changes iu the operation of the factory were contemplated. This was narrowing down the search with a vengeance, and exercised a salutary effect; the malpractice ceased. Evidently the guilty party realised that his crime was likely to be brought home to him, and so, in his wisdom, lie hesitated to imperil his safety any more. The inspecting practice thus initiated has ever since been maintained, but no further complaints from customers have been received. The X-ray apparatus has proved an excellent check upon indifferent work; no goods are sent out without being passed through the machine. Another interesting discovery was made which cannot fail to exercise a far-reaching influence upon this limited circle of trading. By means of the ultra-violet rays the origin of the pearl can be determined. That is to say, the Cingalee pearl can he definitely associated with! the waters washing the

shores of the island of Ceylon; the West Australian pearl with the seas under the Southern Cross; the Japanese pearl with Eastern waters, and so on. Tjp sea of origin exercises a distinctive characteristic! upon the pearl, and one as assertive and as unequivocal as the place and date stamp used for the cancellation of the franking of a letter. It is. impossible to confuse one with another. Thus discovery will tend to discourage' one form of fraud. Conceding that the' product of a specific field has, or through the subtle, fickleness of fashion attains, pre-eminence over rivals found in other parts of the world, and so succeeds' in commanding a higher market price, it will he useless for the unscrupulous trader to resort to pahning-off to gain the higher reward. Investigation by the ultra-violet rays will completely refute his moist strenuous assertions and ostensibly supporting documentary evidence. Under the rays the difference is so strongly emphasised as to admit of no dispute. This is not surprising. The pearl is an impurity which, from, its limpid beauty has become highly prized, and the character of the fluorescence varies according to- the nature w impurity. Iu the cold, unromantic guage of the mineralogist the' pearl 10 merely carbonate- of lime, and the changes can be rung upon this primary material to an endless degree, according to the- other chemicals which are found in company, and which; vary throughout the waters of the world. The impressing of the X-rays and their consort, the ultra-violet rays, in the cause of crime-detection —the term is used in its broadest sense —is only in its infancy. It is capable of illimitable development, and each advance brings some startling, if not dramatic, discovery. The rays are being used for the detection of adulteration, and in this field many unsuspected and regrettable malpractices have- been unmasked. Truly the way of the transgressor is being made exceeding hard by the application of scientific discovery.