[LB005009], Letter from Thomas Alva Edison to Edward Hibberd Johnson, July 21st, 1879


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[LB005009], Letter from Thomas Alva Edison to Edward Hibberd Johnson, July 21st, 1879

Editor's Notes

I shipped you Saturday an instrument which I am absolutely certain will prove perfectly satisfactory in every respect. They have the merit of being simple, convenient and cheap, and not at all liable to get out of order. You will [perceive?] that he chalk is now in a perfectly closed reservoir. The chalk is a phosphate of Soda one and of all substances tha is hte only perfect one. It seems to be absolutely perfect lasting days when exposed to the air. The salt is perfectly neutral, does not change. ou may find a crystallization on the surface of the chalk when they arrive as I fear the were so too thoroughly. They work just the same whether wet or fully wet. We make a concentrated solution of Phosphate of Soda then dilute with 1/2 bulk water, wet with letter copying brush. The surface is the smoothest of all the chalks and never changes without ou saturate the chalk too much then it crystalizes out. With the receiver in the form sent we gain all the margin possible, as when on the old machine it was hard to hear owing to distance away we can with this get the same loudness. The handle goes easier andthe whole thing is better. We send 8 more next week 4 of which will have a different kind of handle and polished mahogany boxes and 2 others will cotain the Inertia Telephone transmitter, that will not get out of adjustment, is adjusted in a second costs 20 cts and can whisper 25 feet away and get talk 3 inches from it. Hereafter we will send 1/2 Inertia and 1/2 regular until we use up the blanace of Bergman transmitters then by that time we can hear your decision as to the one you want. For the first time I feel perfectly at eas on the Telephone. We are going to set up a pair in NY next wek on standard-- YOu know I would not do this if I was not perfectly satisfied. If there are crystallizations just sponge them off with water and it will thereafter be all right. I state on [?] that these chalks will not need wetting more than twice each year. Batchelor writes you further details. [perhaps select this with quotes from Batch as annot]




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Thomas A. Edison Papers, School of Arts and Sciences, Rutgers University
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