DEFEATING CRIMINALS.

Hauraki Plains Gazette, Volume XXXV, Issue 4710, 11 June 1924, Page 4

DEFEATING CRIMINALS.

SEBVICBS or SCIENCE.

(By

Dr F. W. Crossley-Holland,

B.Sc.,

F.C.S., D.C.L.) Daily and hourly the criminal enlists in his service the manifold resources of science, and turns to evil account every promising discovery that inventors and research workers have conceived for the benefit of the community, and not for its disservice. Human nature being what it Is, we shall probably have the wrongdoer, like the poor, always with us, but I for one, thanks to experimental study, venture to think that the days (or years) of successful organised crime are numbered. Applied chemical science is freely made use of by several classes of criminals, and notably by forgers ami base coiners. Criminal practitioners who exercise their misguided activities through the agencies of paper, textile fabrics, and metals must obviously depend for their success upon a knowledge of the : properties of those substances, and, therefore, infinite patience and long training are the self-imposed tasks of the experts. When it suits his purpose the enterprising criminal turns to account the scientific methods introduced by those whose business it is to detect him. THE PART OF CHEMISTRY. Chemistry plays many and important parts in detection. In suspected cases of death by poison it is reiled upon largely, and so exact are the results of chemical methods that in many eases the original poison employed can all be recovered and presented exactly as it was used. Very minute qiulntities of poisons can be detected with certainty. Strychnine, for instance, can be leadily detected at a dilution of one part in one million parts. -

Whilst chemical methods cover by far the majority of toxic substances likely to be employed for poisoning purposes, there remain certain poisons which give no chemical reactions of detective value. Science is not nonplussed by this, however ; it promptly enrols the aid of physiological reaction.

I have in mind a potent vegetable poison which' refused to be detected by any known chemicaj means. What is to be done 1 When chemical methods have failed, a definite amount of the suspected substance is injected into the veins of a small animal of ascertained weight. The poison is

soon recognisable by the symptoms

that it induces in the animal. By means of a suitable delicate apparatus these symptoms cad be re ’ corded graphically and the identity of the causative poison fixed beyond doubt. Before Hie days of detective chemical science there was no certain method of differentiating between similar stains upon clothing. Now-a-days practically no stain or mixtuie of stains can escape exact identification. Dyes in forged Treasury Notes, the chemical composition of Inks used in forgery, .the constitution and composition of various papers, etc., are now as an open book in the chemical laboratory. CONSTRUCTED FROM A HAIR. The microscope plays a very important part in detection. Through it bloods from different sources of life—although indistinguishable from ■one another to the naked eye present unmistakable distinguishing characteristics. Human and other animal hairs all possess differences peculiar to themselves; the microscope reveals these faithfully. Io such a degree has the science or micro-criminology attained that experts can actually “construct the suspected person from a mere fragment of hair, just as prehistoric monsters are “reconstructed’’ from a single fossil bone. Similarly, the microscope is of the utmost value in determining the erstwhile ownership of infinitesimal portions of human skin, and even minute body scales.

Paper and fabrics, such as silk, wool, cotton, flax, etc., have their own microscopic characteristics —a fact of the greatest detective value. In one case a hatchet had to be examined to ascertain whether it had been wiped with a. cloth or a piece of newspaper. An examination of the surface with a magnifying glass showed that some specks were adhering to the rough edge of the instrument. These specks were examined under a microscope, and proved to be fibrous. When treated with a particular chemical reagent fibres of cotton wool are stained pink, and those of newspaper manufactured from wood pulp fibre yellow. Furthermore, the form of wood pulp fibre is different from that of cotton. A number of the specks on the hatchet showed the characteristics of cotton fibre, and the conclusion reached was that the hatchet had been wiped with a cloth, and. not with a paper belonging to the suspect. Further, microscope examination of the hatchet showed that the traces of blood were not human, but that of a pig- These facts exonerated the innocent suspect. Science thus protects the inbeent as it exposes the guilty.

The X-ray,s are found constantly of

value in a variety of ways. Small valuable substances hidden away in. wood or any other organic matter'become visible. X-rays have made the path of the smuggler, and especially, that of the picture forger, vrey diliicult. ULTRA-VIOLET RAYS. Recently a large number of French war bonds were stolen after they had been paid: and candled. A forger by means of bleaching chemicals removed the handwritten date of payment and printed in a new date of issue and presented the bonds for payment. Payment was made; but presently suspicion arose. One of the suspected bonds was submitted to the ultraviolet ray apparatus, with the startling result that the bleached out date of original payment showed up clearly, and the date of issue substituted for the original date of issue did not show up at all. This contitutes a triumph for th? detective utility of the ultra-violet rays, which .succeeded in convicting the manipulator of the bonds. The science of spectroscopy plays an important part against the criminal. By the aid of the spectroscope a bootlace with stains upon it was examined. One of the stains gave spectra identical with those given by the paint on a certain bedstead, and from this fact it was established that tho bootlace had been used to strangle tin invalid by semi-hanging from his bedstead. The lace had afterwards been replaced in the boot. The result forms a remarkable testimony to the rsources of science.

Instances might be multiplied of the truly protean parts that applied science is playing in the direction of crime and the criminal. May it not well be inferred that the time will come when the escape of the criminal will be well-nigh impossible ?