St Nicholas [serial] . shell is the zinc plate, to which issoldered a binding-post to hold the wire. Next,inside of this, is a porous paper lining for insula-tion. Extending down into this is a solid carboncylinder—any shape will do —surrounded bypowdered carbon wet with sal-ammoniac solu-tion. Sawdust would do in place of the carbonpowder, but would not be quite so good. Thepitch is poured into the top of the battery to pre-vent the evaporation of the moisture. These bat-teries come in a paper box, so they can be placedtogether, but do not let the metal parts come incontact, which would soon
St Nicholas [serial] . shell is the zinc plate, to which issoldered a binding-post to hold the wire. Next,inside of this, is a porous paper lining for insula-tion. Extending down into this is a solid carboncylinder—any shape will do —surrounded bypowdered carbon wet with sal-ammoniac solu-tion. Sawdust would do in place of the carbonpowder, but would not be quite so good. Thepitch is poured into the top of the battery to pre-vent the evaporation of the moisture. These bat-teries come in a paper box, so they can be placedtogether, but do not let the metal parts come incontact, which would soon ruin them. Clement B. Davis. CURIOUS STRINGY EFFECTS ON A NEGATIVE Oakland, St. Nicholas : I am sending you a piece of a filmwhich has not been exposed. I opened the film to seewhat it was like and found these funny lines on it. Willyou please tell me what has caused them ?Your interested reader, Alma R. Lavenson. The markings on the film submitted are trace-able to the shutter on the camera having leaked. striking on the sensitive film. The irregularityof the lines is due to the camera having beenmoved about while the shutter was open. We areinclosing another negative showing markings ofthe same kind but more plainly. —EastmanKodak Company. the curious negative appearance ofa photograph Minneapolis, St. Nicholas: We have been wondering if youcan tell us how it happened that this picture, instead of
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Keywords: ., bookcentury1800, bookdecade1870, bookidstnicholasserial371dodg
