6i4 



NATURE 



[April 30, 1896 



sensitive surface of the photographic film. I have obtained 

 considerably better results with a finely ground sample of 

 tungstate of calcium, prepared for me by Messrs. Hopkin and 

 Williams. This may be used either in loose powder or made 

 up with gum into a paste and dried, 



"With this substance it is easy to obtain sharp and fully- 

 exposed negatives of the hand in from five to ten seconds with 

 a moderately excited tube, with which, with ordinary arrange- 

 ments, one to two minutes' exposure would be necessary. 



" I have also tried some special plates prepared for me by 

 Messrs. Marion, into the sensitive emulsion of which fluorescent 

 substances such as powdered fluor-spar and calcium tungstate 

 were introduced before application to the glass. Though the 

 results so far obtained by this method are not very satisfactory 

 owing to granularity, the presence of the fluorescent substance 

 in the photographic film appears undoubtedly to increase its 

 sensitiveness to the rays. 



" There is a wide field for further research on the lines above 

 indicated, both with regard to suitable fluorescent substances 

 and the best method for their application." 



A paper by Dr.Ferdinando Giazzi, of the Regio IstitutoTecnico, 

 Perugia, is of importance in this connection, and the following 

 translation of it, by Mr. G. H. Baillie, will be useful to chemists 

 who are preparing fluorescent salts for use, with Rontgen rays : 



" Some days ago Prof. Ruata called my attention to the tele- 

 gram sent by Edison to Lord Kelvin, and published in Nature, 

 according to which calcium tungstate, when suitably crystallised, 

 showed fluorescent phenomena under the action of X-rays in a 

 far more marked degree than barium platino-cyanide. 



" I immediately consulted Prof. Bellucci, who informed me 

 that calcium tungstate could be easily obtained from either sodium 

 tungstate or tungstic acid, two commercial products selling at a 

 low price. Having obtained these from the firm of Bonavia of 

 Bologna, I set to work and produced some calcium tungstate, 

 but in an amorphous form, which was, as far as I could test with 

 the coil at my disposal, insensible to X-rays. I shall not 

 describe all the attempts I made by wet and dry processes to 

 obtain the salt in the desired form. I merely say that I never 

 have dealt with a body so intractable. The follgwing is the 

 process I finally adopted in preparing it for surgical purposes. I 

 treated a dilute aqueous solution of sodium tungstate with a 

 solution of calcium chloride, given to me by my colleague Prof. 

 Corneliani ; I thoroughly washed the resulting pure white pre- 

 cipitate, and dried it at a gentle heat in a porcelain capsule. Next 

 I made a small hole in a piece of fresh retort-carbon, and filled 

 it with the precipitate, which I fused and boiled by means of a 

 small flame from an oxyhydrogen blowpipe. After boiling for 

 some seconds (at a bright white heat), I gradually removed the 

 substance from the hottest parts of the flame, so that solidifica- 

 tion took place only after a few minutes. In this way I obtained 

 five globules of calcium tungstate of the required structure. I 

 powdered them in an iron mortar and sifted the powder on to a 

 gummed card, which I exposed in the camera to Rontgen rays. 

 The result was most striking ; I saw at once the shadow of the 

 skeleton of my hand more clearly than I ever have with other 

 preparations. A surgeon with this product, good Crookes' tubes, 

 a large coil, and an apparatus such as I have arranged, could 

 certainly dispense with the tedious process of photography. 



" I publish this note for the assistance of those who perchance 

 have not yet succeeded in preparing the invaluable tungstate in 

 the desired form." 



So far as the utility of the method of reducing exposure 

 by means of fluorescent screens is concerned, the advantage 

 gained must be understood only in a comparative sense. Some 

 investigators obtain excellent results without the use of the 

 screen in less time than others with a screen. Dr. John Macin- 

 tyre, who has sent us several communications previously upon 

 his work with Rontgen rays, has something to say about the 

 reduction of exposure by screens, in a letter just received. He 

 remarks : 



" The object of this note is not to minimise the importance of 

 any aid which the physicist may place in the hand of the 

 surgeon. I have been aware of this new method, but my 

 experience in practice has not encouraged me meantime to 

 pursue it largely, because of want of time in developing what I 

 consider of greater importance, viz. a better Crookes' tube. In 

 surgery what we require may be divided into two parts : ( i ) 

 rapid views of objects, and (2) permanent records. In practice 

 we must have for the former not photographs but direct vision, 

 and for the second, of course, rapid exposures. Now it may 



NO. 1383, VOL. ^Z\ 



occasionally happen that a permanent record is desirable of 

 what must be done almost instantaneously. That point I think 

 ought to be reached ere long. 



"Some weeks ago I recorded a photo of the elbow-joint in 

 if minutes, and that at a time when we did not understand the 

 tubes as well as now. Since then I have obtained records of 

 metallic objects in half a second, and the bones of the hand in 

 six seconds, without the aid of fluorescent screens. What we desire 

 most, however, in practice is a better Crookes' tube for fluorescent 

 screens in direct vision. At present I go while the tube is being 

 exhausted, and test the result before it is taken off the pump. 

 When I am examining an object with the screen, or about to 

 photograph, I heat the tube and keep the current passing 

 through until the maximum effect is obtained. I have now seen 

 by this means the diff"erent bones of the extremities and joints % 

 moreover, I have no difficulty in seeing through the body itself. 

 The spine ribs, sternum, clavicle and scapula can be seen ; and 

 I have shown to several medical men the shadow of a coin in 

 the gullet (impacted for six months), opposite the fourth dorsal 

 vertebra. Foreign bodies in the extremities are, as a rule, 

 easily seen. 



" For the examination of the cavities inside the head, e.g. the 

 antrum, or mouth, or pharynx, also the teeth, I now place fluor- 

 escent screens in the mouth, and the Crookes' tube outsidfe, either 

 above or below the level of the buccal cavity as required, and 

 sharp images are thus obtained on the screen of not only foreign 

 bodies, but also of the bones of the face, and roots of the teeth 

 as well. 



"Other tissues than the bones are now yielding. I have 

 photographed the side of the neck, and shown the tongue, 

 hyoid bone, the pharygeal cavity, cartilages of larynx and 

 trachea of the living adult subject. 



" At present we cannot afford to ignore any aid, and hence 

 we are glad to have such hints as the fluorescent screens in 

 photography ; but it is not unlikely that all such will be more 

 or less dispensed with as a better source of the X-rays is 

 obtained, viz. a still better Crookes' tube." 



Since the above was written, and in consideration of the 

 question at issue, Dr. Macintyre informs us that he has made a 

 further series of experiments on the question of rapid exposures. 

 The tube used was one of the now well-known ordinary focus 

 tubes, made in Glasgow, He has obtained a well-defined 

 image of metallic objects, and distinct, though faint, image of 

 the bones of the fingers with one flash of the Crookes' tube, 

 produced by a single vibration of the mercury interrupter, a large 

 coil giving an eleven-inch spark, and, of course, without using 

 any fluorescent screen. What the extent of the time of ex- 

 posure was cannot be said, but he describes it as an unknown, 

 unmeasured, small fraction of a second. In another experiment 

 he was able to obtain a distinct image of the bones of the fore- 

 arm with sixty similar flashes of the tube. 



Prof. O. N. Rood found indications of reflection of Rontgen 

 rays from a platinum surface on March 9, and on March 13, 

 after an exposure of ten hours, he obtained a good negative, 

 capable of furnishing prints, of a piece of iron wire netting 

 reflected from a sheet of ordinary platinum foil and through a 

 plate of aluminum {Science, March 27). The conclusion he 

 arrived at from iflSpection of the image was that " in the act 

 of reflection from a metaUic surface the Rontgen rays behave 

 like ordinary light." Experiments made to ascertain the per- 

 centage of the rays reflected, indicated that platinum foil reflected 

 the i/26oth part of the X-rays incident on it at an angle of 45°. 



Upon the question of reflection and refraction of Rontgen 

 radiance. Prof. Pupin pointed out in his paper read before the 

 New York Academy of Science, on April 6, that it was dis- 

 cussed by Prof. Rontgen in Sections 7 and 8 of his origina 

 essay. Neither by photography nor by the fluorescent screen 

 could Prof. Rontgen detect an appreciable refraction with cer- 

 tainty. A reflection from metallic surfaces in the immediate 

 vicinity of a photographic film was detected, " but," translating 

 Rontgen's own words, " if we connect these facts with the 

 observation that powders are quite as transparent as solid bodies, 

 and that, moreover, bodies with rough surfaces are, in regard to 

 the transmission of X-rays, as well as in the experiment just de- 

 scribed, the same as polished bodies, one comes to the con- 

 clusion that regular reflection, as already stated, does not exist, 

 but that the bodies behave to the X-rays as muddy media do 

 to light." " In face of these observations," continues Prof. Pupin, 

 " Prof. Rood's and Mr. Tesla's experiments must be interpreted 

 as a confirmation of Prof. Rontgen's results, and not as a 



