Page:Popular Science Monthly Volume 41.djvu/97

 of them by placing pieces of marble or lithographic stone in a dilute solution of chloride or sulphate of manganese. The hope of success is all the more legitimate because carbonate of lime has already permitted the imitation in this way of several natural minerals, particularly of limonite, an iron mineral, and bauxite, or the mineral of aluminum. But the experiment has not been successful, and, instead of the desired black deposit, we get only chocolate-brown flakes having no resemblance to the substance of the dendrites.

Seeking for the causes of this want of success, I have found, by analysis, that the dendrites said to be of manganese contain oxide of iron, in minute proportions it is true, but in proportions that seem to be sufficient. And the addition of traces of ferric salts to the solution of manganese salt has really determined the deposit on the limestone surface of a perfectly black compound, presenting in many cases the exact form of the dendrites of Nature. I have in the museum specimens that leave no doubt on the subject, the inferiority of which to the models which I sought to copy is most probably due to the inferior slowness of the process of producing them.—Translated for The Popular Science Monthly from La Nature.



THE rapid development of science and its numerous applications in the industrial arts are leading to a general recognition of its importance as a factor in the material and intellectual progress of the age. The aid of science is now invoked in every department of human activity, and, judging from what has already been accomplished, we can not perceive any indications of a limit to its useful applications in the industries.

While the general outlook encourages optimistic views in regard to the present and prospective advantages that may be realized from the applications of science, we should not overlook the shadows involved in its progress, which seriously interfere with its own advancement, and at the same time increase the difficulties attending original investigations relating to many industrial problems.

The scope and extended range of modern science, that necessitate a subdivision of its lines of research into numerous branches,