eee 
yet, but the one that also here, just as with the piece of bar-iron, 
the direction of the fibres could be seen with the bare eye, as well 
as a very distinet difference between the drawn and the compressed fibre. 
As to the structure and formation of the carbide crystals nothing 
could be fixed at this first experiment, I do not doubt however, 
but also here the results will be satisfactory. 
Worth mentioning still is the etching of a cylinder-shaped piece of 
cast-steel, which was submitted to electrolysis for 36 hours. Although 
outwardly no etched design could be seen, a porous coat of + */, inch 
of some iron-carbide appeared to be have been formed, which, coming 
in contact with the air, was apt to oxidize, could be cut with a knife, 
and in the incision glittered like metal. When analysed the iron-per- 
centage proved to be 91'/, °/,. 
The great results, obtained also here, are a stimulus to me, to 
investigate this matter later more thoroughly. 
Those experiments suggested to Prof. ScHROEDER VAN DER KOLK the 
idea, whether crystals of minerals treated in this way, would show 
a design. Considering the results, obtained with copper-alloys, a piece 
of a copper-ore was used for the first experiment. After an hour, 
also this material showed a distinct etch-design, which is probably 
connected with a crystal formation. Not to be led away from my 
subject, L will only just mention the phenomenon. 
Before concluding, I will resume the advantages, gained by the 
way indiceted. 
Lely, Results having been obtained, where the ordinary grinding- 
polishing- and eteh-methods had failed. 
Quy The obtained preparations show a far more detailed design, 
which stands out in much stronger relief than the ordinary etch-slide. 
sly) Tt is not necessary to finish off the slides half so carefully, 
as the tempering-method requires. 
gele From different alloys erystals or fragmentary crystals have 
been detached which permit of analysis and show remarkable 
differences with the average percentage of the alloys. 
The good results are a sufficient recommendation for practical 
purposes, time may still be saved by connecting many apparatuses 
