Proceedings of the American Association for the Advancement of Science, Volume 29 |
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Page 115
... selenium , " and the manipulations devised by previous experimenters ; but the final result of our researches has widened the class of substances sensitive to light vibrations , until we can propound the fact of such sensitiveness being ...
... selenium , " and the manipulations devised by previous experimenters ; but the final result of our researches has widened the class of substances sensitive to light vibrations , until we can propound the fact of such sensitiveness being ...
Page 116
... selenium . Selenium . In the year 1817 , Berzelius and Gottlieb Galin made an examination of the method of preparing sulphuric acid in use at Gripsholm . During the course of this examination they observed in the acid a sediment of a ...
... selenium . Selenium . In the year 1817 , Berzelius and Gottlieb Galin made an examination of the method of preparing sulphuric acid in use at Gripsholm . During the course of this examination they observed in the acid a sediment of a ...
Page 117
... selenium , as Berzelius showed , a non - conductor . Knox2 discovered in 1837 , that selenium became a conductor when fused ; and Hittorff , 3 in 1851 , showed that it conducted at ordinary temperatures when in one of its allotropic ...
... selenium , as Berzelius showed , a non - conductor . Knox2 discovered in 1837 , that selenium became a conductor when fused ; and Hittorff , 3 in 1851 , showed that it conducted at ordinary temperatures when in one of its allotropic ...
Page 118
... selenium was found to have all the resistance required ; some of the bars employed , measuring as much as 1400 megohms -a resistance equivalent to that which would be offered by a telegraph wire long enough to reach from the earth to ...
... selenium was found to have all the resistance required ; some of the bars employed , measuring as much as 1400 megohms -a resistance equivalent to that which would be offered by a telegraph wire long enough to reach from the earth to ...
Page 119
... selenium at that time . They confirmed Hittorff's observation that the temperature of mini- mum resistance of granular selenium was somewhere about 210 ° C. , and that at 217 ° C. ( the fusing point ) , the resistance suddenly in ...
... selenium at that time . They confirmed Hittorff's observation that the temperature of mini- mum resistance of granular selenium was somewhere about 210 ° C. , and that at 217 ° C. ( the fusing point ) , the resistance suddenly in ...
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acid action Albany Alexis Caswell apparatus Association astronomers ATURE B. A. Gould battery beam binary stars Born Boston Cambridge cell Charles Chem chemical Cincinnati COEFF College color comet Conn determination Died discovery disk distance effect electric empty pipette energy ether experiments F. W. Putnam forest FRIC friction George Haven heat Henry Henry's inch instrument Iowa James John light liquid Louis magnet Mass measures mechanical metal method molecular molecules motion muscle Nashville O. C. Marsh observations Observatory Ohio P. O. Box Permanent Secretary PERMANENT SUBSECTION phenomena Philadelphia plant plate President produced Prof protoplasm required to empty researches Saratoga Springs schools scientific Seconds required sections selenium Spindle Standing Committee stars substance surface tellurium TEMPER temperature Tenn theory tion Univ Washington William wire Yale College York
Popular passages
Page 92 - Concerning each of which, many seem to have fallen into very great errors ; for by invention, I believe, is generally understood a creative faculty, which would indeed prove most romance writers to have the highest pretensions to it ; whereas by invention is...
Page 80 - ... which certainly form a new era in the history of electricity and magnetism, should not have been more fully described before this time in some of the English publications; the only mention I have found of them is the following short account from the Annals of Philosophy for April, under the head of Proceedings of the Royal Institution :
Page 131 - A large number of trials of this apparatus have been made with the transmitting and receiving instruments so far apart that sounds could not be heard directly through the air. In illustration, I shall describe one of the most recent of these experiments. Mr. Tainter operated the transmitting instrument, which was placed on the top of the Franklin School House in Washington, DC, and the sensitive receiver was arranged in one of the Fio.
Page 73 - Around this horse-shoe 540 feet of copper bell-wire were wound in nine coils of 60 feet each ; these coils were not continued around the whole length of the bar, but each strand of wire (according to the principle before mentioned) occupied about two inches, and was coiled several times backward and forward over itself. The several ends of the wires...
Page 92 - By genius I would understand that power, or rather those powers of the mind, which are capable of penetrating into all things within our reach and knowledge, and of distinguishing their essential differences.
Page 131 - Mr. Bell, if you hear what I say, come to the window and wave your hat.
Page 93 - But facts were important to me, and saved me. I could trust a fact, and always cross-examined an assertion. So when I questioned Mrs. Marcet's book by such little experiments as I could find means to perform, and found it true to the facts as I could understand them, I felt that I had got hold of an anchor in chemical knowledge, and clung fast to it.
Page 122 - ... telephone from one place to another without the necessity of a conducting wire between the transmitter and receiver. It was evidently necessary, in order to reduce this idea to practice, to devise an apparatus to be operated by the voice of a speaker, by which variations could be produced in a parallel beam of light, corresponding to the variations in the air produced by the voice.
Page 78 - Kritik, Ohm's theory was named a web of naked fancies, which can never find the semblance of support from even the most superficial observation of facts ; ' he who looks on the world/ proceeds the writer, ' with the eye of reverence must turn aside from this book as the result of an incurable delusion, whose sole effort is to detract from the dignity of nature.
Page 118 - To ensure that temperature was in no way affecting the experiments, one of the bars was placed in a trough of water so that there was about an inch of water for the light to pass through, but the results were the same ; and when a strong light from the ignition of a narrow band of magnesium was held about nine inches above the water the resistance immediately fell more than two-thirds, returning to its normal condition immediately the light was extinguished.