Letter from Erasmus Darwin to James Watt, 1795/04/28

Darwin writes to Watt of his experiments with gases and now seems to be treating patients with oxygen and arsenic.

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Dear Sir,

I am much obliged to you for your letter of instructions, which I have avail’d myself of. And shall be obliged to you further, if you will please to send me, as soon as you can, another _ hundred of Exeter Manganese, and also another large air-holder and pipe, and another silk-bag with box-wood spiggot and faucet. – but if the latter are not ready, please to direct the manganese to be sent, as soon as may be, by first carrier alone: and the others as soon as is convenient after it.

For I expect a person to come to Derby to breathe oxygene on the 4th or 5th of May and I have a Lady now, who consumes a pound or two of manganese every day. – sometimes she takes it pure, but generally with half common air, and is refresh’d by it, and thinks her headachs much relieved by it, or by a saturated solution of arsenic, which she takes also, from 3 to 5 drops thrice a day.

Arsenic I believe strengthens the stomach, and by sympathy the action of the heart; as I observed it to cause a palpitation of the heart for several days, during the time it was taken. It certainly cures the ague, when the bark fails, and I think relieves Cephalaea, even when decaying teeth are the remote cause. I put any quantity of arsenic in powder into a florence flask, and boil it for an hour gently in less water by half than will dissolve it. I put an ounce of this saturated solution into a two-ounce phial to ascertain the size of the drops, and give from 3 to 5 (and even to ten drops) thrice a day.

I have not yet used your Hydro-Carbonate, but intend to use it in consumption, to promote slight degrees of sickness.

I desired Johnson to send me Dr Beddoes’ new edition, but have not yet received it. I have recommended your apparatus to the Infirmaries of Nottingham and Shrewsbury.

Mrs Darwin joins me in our best compliments to Mrs Watt with, dear Sir,

your obliged friend

and obed. serv.

E Darwin

Derby Apr. 28-95