Letter 4 from Alessandro Volta to 3rd Earl Cowper

Pavia 20th April 1779

By Gill Cordingley & Maria Porter

Cowper will send Volta a eudiometer that has been manufactured in London. He has also ordered a replica of “Volta’s Pistol” to be made up, but delivery has been delayed because the ship carrying it has been captured by the French. He hopes to see Volta in Florence but is unable to offer him any accommodation! Cowper will send a covering letter with the translation of the work of Tiberius Cavallo. Volta has also been in correspondence with Dr Carlo Alfonso Guadagni, his opposite number at the university of Pisa, who was a friend of Cowper’s. Dr Guadagni often worked in Cowper’s “cabinet” and was much envied by other practitioners in Florence because he had free access to Cowper’s expensive apparatus. It seems that there had been complications with Guadagni’s attempts to replicate some of Volta’s experiments.

Altezza

Son debitore di risposta a due lettere di V.A. Ricevei la prima varj giorni sono; e come questa mi avvisava che avrei recevuto da un Vetturale una macchinetta del. Sig. Magellan; e d’indi a poco la traduzione del trattato di elettricità del Sig. Tiberio Cavallo, speditami una cosa e l’altra in dono da V.A., così volli aspettare che le predette cose me giungiessero, per ragguagliarla della ricevuta, e fargliene i più umili ringraziamenti. Coll’ ultimo ordinario ricevetti dalla Posta il libro indicato, e la seconda lettera di V.A.; ma la macchinetta, che dovea portarmi il vetturale, non è ancora comparsa. Non deggio pertanto differire a compir al mio debito e verso V.A. e verso il Dottore Fossi, che di gentilezza mi ha prevenuto, nel regalarmi la sua bella traduzione, che ho già letta quasi per intiero con gran piacere e frutto. Rendo altresì grazie a V.A. per la lettera, che si è compiacciuta accludermi dal Dr. Guadagni, compiacendomi assai, che i miei Conduttori abbiano anche presso a lui avuto buon incontro.

In luogo di amalgama di mercurio io ho trovato che la polvere di carbone impastata con sego o grasso è eccellente, sporcandone i cuscinetti, per eccitare l’elettricità del vetro. Mi pare che riesca meglio che l’amalgama istesso, segnatamente in tempo umido; e ciò perchè il grasso tien lungi l’umiditadà dal vetro: ed avvegnachè questo grasso di cui sono spalmati i cuscini sporchi il vetro, nulla meno l’elettricità vi si eccita vigorosissima. Si può quest’impasto di grasso e carbone o tener preparato, e distenderne all’uopo una porzione sulla seta di cui son ricoperti i cuscini; oppur basta ungere di sevo, o sporcar di mantecca, o di grasso i cuscini medesmi; e dopo spargervi sopra la polvere di carbone, e impastarlo così stroppicciando alcun poco un cuscino contro l’altro.

Sto faccendo costruire le diverse lucerne ad aria infiammabile, di cui avrò l’onore di presentare a V.A. qualche modello, in un colla descrizione delle medesime. Sono col più profondo ossequio di V.A.

Pavia li 20 Aprile 1779

Umill.mo Dev.mo Obb.mo Servo

Alessandro Volta

 

Your Highness

I owe an answer to two of Your Highness’ letters. I received the first some days ago and as it mentioned that I would receive a delivery of a small machine by Mr. Magellan and shortly after the translation of the treatise about electricity by Mr Tiberio Cavallo, both of them sent to me as a gift by Your Highness, I decided to wait until the above mentioned would arrive to let you know that I received them and to send you my most humble thanks. With the latest delivery I received by the post the above mentioned booklet and Your Highness’s second letter; but the small machine that should have been delivered has not appeared yet. I mustn’t therefore delay my duty both towards Your Highness and Dr. Fossi1, who has shown me a great kindness in giving me an excellent translation which I already have almost completely read with great pleasure and profit. Also I thank Your Highness for Dr Guadagni’s letter that you kindly enclosed where my conductors found favour with him too.

Instead of a mercury amalgam, I have found that charcoal dust mixed with tallow or fat is excellent, smearing the pad will induce the electricity of the glass. It seems that it would even be more successful than the amalgam especially in humid weather because the fat keeps the wetness away from the glass and although the fat with which the pads are smeared will make the glass dirty and the electricity is much stronger. You can have this mixture of fat and charcoal ready made and put the portion that you require on the silk that covers the pads; otherwise it is enough to grease with tallow or pomade (hair oil) or fat; and after spreading the coal dust mix them by rubbing for a little while one pad against the other.

I am having made the various lamps with inflammable air, of which I will have the honour to present to Your Highness some of the models, one of which with their description. I remain with very deep respect to Your Highness.

Pavia 20 April 1779

Your Most Humble, Your Most Devoted,Your Most Obsequious Servant

Alessandro Volta

Note: 1 Dr. Fossi – no reference found.

This page was added on 07/07/2013.

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