554 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
stitutes an advantage sufficiently great to compensate for the difficulties 
of its application. 
We have, with respect to this question, had to investigate the subject 
by special calculations, no one being in a position a priori to answer it. 
These investigations have, however, hitherto not led to any positive 
results. It remains, in fact, still highly problematic whether there be any 
problem in practical optics the solution of which may be approached by 
the existence of a glass possessing the characteristics of the artificial opal. 
Nevertheless, the substance in question interests us in a high degree. 
We recognize in its appearance a valuable attempt to extend the range 
of optical means, and an incitement for new studies in the production of 
artificial glasses. As we ourselves, in conjunction with Dr. Schott, have 
worked in this direction for a period of ten years, and intend to continue 
our researches, the outcome of your experiments is indeed full of interest 
to us, quite irrespectively of the question whether your material affords 
a means of immediate practical application or not. For this reason we 
entertain a wish of at least rendering your researches available for con- 
tinuation in our own experiments in glass smelting. 
We make to you, therefore, the following proposition : — 
We offer you to defray the expenses of your past experiments 
(. . . . francs), provided you agree to communicate to us the composition 
of, and manner of, fusing your glass with such exact and complete 
directions as to enable Dr. Schott to reproduce it in his laboratory. We 
farther stipulate that you place in our hands a few samples of the 
material obtained by yourself enabling us thus to at once proceed with 
experiments on its properties ; that you authorize us, or Dr. Schott, to 
compound your glass according to your directions, in order that we may 
obtain material for practical experiments , and also to utilize the process 
indicated by you in researches aiming at the production of other similar 
glasses. 
It is to be understood that you retain all rights as to priority, in 
particular the right of publishing your experiments, inclusive of the 
composition of your glass and the mode of fusing it, before we publish 
anything on the subject or make any attempt to utilize the glass com- 
mercially. It is, however, to be agreed that you promise to suspend 
such communications to others on the compositions and production of 
the glass for one year , in order that, in the meantime, we may find 
sufficient time to exhaustively investigate the matter. 
As this proposition agrees entirely with the first offer which you 
made in your letter of the 28th Sept., excepting only that in the present 
proposition we cede to you further rights which we do not consider 
ourselves justified in claiming for ourselves, we assume that the above 
will meet with your approval.’ 
And after having received the desired communications from Mr. 
Brun, the firm of Zeiss wrote again : — 
‘We should consider it very inappropriate to any longer insist upon 
your continuing to keep secret the general results of your studies — i.e. 
the artificial production of amorphous silica and the establishment of 
its optical character. These results are of such great scientific interest 
that you should, in order to establish your priority, forthwith publish 
them. Our interest in the continuation of your work would thereby not 
be affected in the least. In fact, had even those results been published 
