6i4 



NATURE 



[April 25, 1901 



The foregoing facts give the clue to the direction in 

 which the steel microscopist must look for danger with 

 reference to rupture under vibration. 



In a brief article it is difficult to do more than give 

 suggestions, but it is necessary to point out that the 

 majority of published micrographs exhibit a single plane 

 of transverse section. Such representation can give only 

 a very partial knowledge of what may be termed the 

 solid geometry of steel. 



To determine this it is necessary, in rolled metals, to 

 make three micrographs in three planes of section at 

 right-angles to each other, namely {a) a tranverse section, 

 {b) a longitudinal horizontal section, (<:) a longitudinal 

 vertical section. From these the exact form in which 

 any constituent exists in the mass can be determined. 



As an example, the case of the constituent sulphide of 

 manganese may be taken. It must be remembered that 

 0*09 per cent, by weight of sulphur corresponds to no 

 less than 0*5 per cent, by volume of manganese sulphide, 

 a very appreciable amount for a micro-constituent. 



In the original ingot during solidification and cooling 

 the sulphide segregates into roughly globular masses 



Fig. 



-Size of original drawing, six inches ; magnificalion, 112 diameters. 

 The magnificalion heie represenied is about 42 diameters. 



On reheating the ingot for rolling, the sulphide 

 liquefies and the liquid globules are elongated in the 

 direction of the rolling, and necessarily to some extent 

 in a line at right-angles to that direction. Hence in a 

 steel plate, the sulphide may present in the three planes 

 of section above specified the appearances exhibited in 

 Fig. 3, which shows that the sulphide is distributed 

 throughout the steel in the form of irregular, oval 

 laminae. 



It will be obvious that the evil mechanical influence of 

 this constituent will be at its minimum along the length 

 of the plate, somewhat greater across the plate, and at 

 its dangerous maximum through the thickness of the 

 plate. 



Perhaps an obstacle to the development of steel works' 

 metallography, even greater than the terror inspired by 

 an unnecessarily complicated nomenclature, is the 

 apparatus, time, care and special reagents supposed to 

 be necessary to obtain, by polishing and etching, a good 

 micro-section. In the advocacy of this view no one has 

 been more earnest than the writer, and for research 

 purposes it is doubtless sound. But for works' purposes, 



NO. 1643, VOL. 63] 



in connection with most steels, it must be confessed that 

 such necessity has been exaggerated. 



The writer has, therefore, pleasure in withdrawing his 

 former view owing to experience having proved that by 

 a very much simplified modification of method, a micro- 

 section may be placed upon the stage for examination in 

 five minutes after it leaves the dead smooth file in the 

 machine shop. This process, which entirely does away 

 with elaborate polishing apparatus or special etching 

 reagents, is as follows : 



Take two pieces of hard wood, 12" x 9" x i", planed 

 dead smooth on one side ; then by means of liquid glue 

 evenly attach to the smooth faces two sheets of the 

 London Emery Works Co.'s Atlas cloth. No. o. Allow the 

 glue to set under strong pressure. Next, by means of a 

 smooth piece of steel, rub off from one of the blocks as 

 much as possible of the detachable emery. This is No. 2 

 block, the other, necessarily. No. i block. 



The steel section, say \ inch thick and \ inch diameter, 

 is rubbed for one minute on No. i block, the motion being 

 straight and not circular ; then, for the same time and in 

 the same manner, rub on No. 2 block. Next place the 

 bright but visibly scratched section in a glass etching 

 dish 3" X I ' X ^", and cover the steel with nitric acid, sp. 

 gr. I "20. 



Watch closely, until in a few seconds the evolved 

 gases adhering to the section change from pale to deep 

 brown and effervescence ensues. Then, under the tap, 

 quickly, wash away the acid and for a minute immerse 



Fig. 



the piece in a second dish containing rectified methyl- 

 ated spirits. Dry the section by pressing it several 

 times on a soft folded linen handkerchief, when it will be 

 ready for examination. The structure will be clearly 

 exhibited, the innumerable fine scratches visible before 

 etching having virtually vanished. 



The micrographs illustrating this article were prepared 

 in a very few minutes by the above process, and have 

 been accurately reproduced by Mr. F. Ibbotson. The 

 writer hopes that this simple and rapid method may 

 help to stimulate in steel works' practice a more extensive 

 study of metallography. J. O. Arnold. 



THE WORK OF THE REICHSANSTALT. 



A THICK quarto volume of nearly five hundred pages* 

 gives a full account of the recent scientific re- 

 searches of the Reichsanstalt. It is impossible, and 

 perhaps not very useful, to attempt in the brief compass 

 of a notice any full description of these varied investiga- 

 tions. All who are interested in physical measurement 

 know that when a paper on any subject is issued from the 

 Reichsanstalt it must be studied by any workers who 

 come after. 



In some respects the volume is sad reading to an 

 Englishman. Problems which originated in England 

 have in too many cases received their final solution from 

 the researches of one or more of the distinguished band 

 of workers gathered round the Director, Prof. Kohlrausch. 



The volume opens with Dr. Thiessen's research on the 



1 Wissenschaftliche Abhandlungen der Phys.kaliscli Techiiischen Reichs^ 

 anstalt. Band iii. Pp. 477. ^(Berlin : J. Springer, 1900). 



