If you Can give me any instructions as to obtaining or constructing a revolving electro-magnet so as to give a succession of sparks, to decompose water &c. Have you used the instrument & does it answer for class experiments? I believe I wrote you that I am (DV) to lecture again in Boston next spring, the subject chemistry, & if you think of any thing in galvanism-electro-magnetism & beyond what is usually exhibited with a deflagrator, a calorimitor, Henry’s electro-magnet &c, I will thank you to name it to me.