AN INTERESTING EXPERIMENT WITH PHOSPHORUS
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EXPERIMENT WITH PHOSPHORUS 193 as it has in England, where the very foremost of English speak- ing physicists have been for ten years urging the basing of explanations in optics upon the ^causally conditioning^ facts of change of wave curvature instead of upon the fiction of rays. As a matter of fact the wave front view point furnishes not only a truer, but a simpler, clearer, and more practicable standpoint for the treatment of geometrical optics, even in the most ele- mentary courses. In conclusion permit me to repeat a remark which I remember making upon the occasion when I was first asked to teach a course in elementary physics, which was as a matter of fact the first subject which I ever taught. I replied to the principal from whom the request came about as follows: "I am very glad that it is physics which you wish me to teach, for a man who cannot in- terest pupils in that subject surely cannot interest them in any- thing. It is a subject which in itself, irrespective of the teacher, is the most fascinating in the whole category, and the man who cannot succeed at it was surely not meant for a teacher.^ I am still of the same opinion. AN INTERESTING- EXPERIMENT WITH PHOSPHORUS. BY NICHOLAS KNIGHT, Cornell College, Mount Vernon, lozva. If a stick of phosphorus five or six cms long is placed in a mod- erately concentrated solution of copper sulphate, a coating of metallic copper will gradually collect on the phosphorus, some- times crystals of copper will be observed, especially on the ends of the piece. A week may be required for the completion of the experiment, and the addition of more copper sulphate may be necessary. The equation which expresses the reaction is as fol- lows: 2P+5 Cu S04+8HaO=5 Cu+2H3P04+5H2S04. An examination of the section on phosphorus in all the text- books at hand failed to disclose any mention of the experiment. It is nevertheless a striking one, and can easily be given in any elementary course.
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Transcript of AN INTERESTING EXPERIMENT WITH PHOSPHORUS
EXPERIMENT WITH PHOSPHORUS 193
as it has in England, where the very foremost of English speak-ing physicists have been for ten years urging the basing ofexplanations in optics upon the ^causally conditioning^ facts ofchange of wave curvature instead of upon the fiction of rays.As a matter of fact the wave front view point furnishes not onlya truer, but a simpler, clearer, and more practicable standpointfor the treatment of geometrical optics, even in the most ele-mentary courses.
In conclusion permit me to repeat a remark which I remembermaking upon the occasion when I was first asked to teach a
course in elementary physics, which was as a matter of fact thefirst subject which I ever taught. I replied to the principal fromwhom the request came about as follows: "I am very glad thatit is physics which you wish me to teach, for a man who cannot in-terest pupils in that subject surely cannot interest them in any-thing. It is a subject which in itself, irrespective of the teacher,is the most fascinating in the whole category, and the man whocannot succeed at it was surely not meant for a teacher.^ I amstill of the same opinion.
AN INTERESTING- EXPERIMENT WITH PHOSPHORUS.
BY NICHOLAS KNIGHT,Cornell College, Mount Vernon, lozva.
If a stick of phosphorus five or six cms long is placed in a mod-erately concentrated solution of copper sulphate, a coating ofmetallic copper will gradually collect on the phosphorus, some-times crystals of copper will be observed, especially on the endsof the piece. A week may be required for the completion of theexperiment, and the addition of more copper sulphate may benecessary. The equation which expresses the reaction is as fol-lows:
2P+5 Cu S04+8HaO=5 Cu+2H3P04+5H2S04.An examination of the section on phosphorus in all the text-
books at hand failed to disclose any mention of the experiment.It is nevertheless a striking one, and can easily be given in anyelementary course.
