Philofophical and Chemical Informatltn. tjj^ 



quently may obviate the deception which has hitherto been praffifed by certain in^^'ifttvd 

 venders of watches. :irti.lDn3ir i: Juoriiiw ynoarij v/;»n / .•onii/.J s^sdJ: 



Lincoln, April Sth, 1799. "O^ iuovMiua \d ,ovilobnooni 



; inoJJfiOitcjqB inyv jiq lloov/ SDifaiffbnq.JcHJ 'jvilrittoiqf. 



Letter from Mr. ff. DAfr, introduffery to the Ettperiments contained in the fubfequent Article, 

 and on tther Subje£fs relative 4^tie J'rogrefsef Scientft -» , • 



SIR, '. _ , , Tirlj ^>;:':'C:^"<''^ '; ^^m'-' .' •;<. s-:^^ > /'o 



I 



SEND you for your Phyfical Journal, experiments and obfervations on the flint contained in 

 'the epidermis and other parts of certain vegetables : thefe experiments have been made within 

 the laft fortrtight. I am induced to make them public fo fpeedily, from the hopes that others, 

 who have greater opportunities and more leifure, may be ftimulated to further refearches on 

 this intcrefting fubjtdt. I doubt not that other plants will be found to contain filex, as well 

 as the reeds, the canes, and the grafles. 



In the Pneumatic Inftitution we have lately made fome experiments on the nitrous phofoxyd 

 (gafeousoxyd of azote), the principle of contagion of Mitchill. When it is mmgled with 

 I of phofoxygen (oxygen gas), animals live in it without fufFering any injury. I have made 

 two infpirations of it pure, without any difagreeable effedls, I have breathed it mingled with 

 'Sn equal qaantityof phofoxygen (oxygen gas) for ibme minutes ; the effeiks produced by it 

 were very peculiar : fliould they be confirmed by future experiments, it will probably prove a 

 valuable medicine. 



In my effay on heat, light, &c. in the Weft-country Contributions, p. 10 1. Ob. 4, an inac- 

 curacy occurs with refpeft to the produdlion of this gas. It is faid " no light is produced 

 ** during thedecompofitionof phofnitrate of ammoniac by heat," In the experiments from which 

 . that obfervation was deduced, no luminous appearance was vifible, as the phofnitrate was 

 mingled with a large quantity of filiceous fand, andflowly decompofedby theheatofan Argand 

 lamp. Lately I have made the experiment in the large way: when the heat is quickly ap- 

 plied and the phofnitrate mingled with but a fmall quantity of fandi a vivid luminous ap- 

 pearance is uniformly perceived. A paper on the nitrous phofoxyd will appear in the next 

 volume of Dr. Beddoes' contributions. 



With the hopes of difcovcring a cheap fubftitute for nitre, I have lately made the phofmu- 

 riates (oxygenated muriates) offtrontianandbarytes. The properties of the firft correfpond with 

 the account I have given of them, in the Weft-counttjK^ontributions, art. Combinations of the 

 muriatic Phofacid, except that its folubility is not fo great as I at firft fufpeiled. The phof- 

 muriate of barytes cryftallifes in plates, and detonates very flightly with charcoal and phof- 

 phorus. A folution of it in water, like that of the phofmuriate of ftrontian, becomes Iiuiu- 

 nous when the fulphuric acid is poured into it. \ 



I would wifli to obferve, that no afFetftation of Angularity induces me to ufe a new nomen- 

 clature. Theory or arrangement of fadts depends altogether on language, i. e. in applying 



certain 



