i 3 0 Cry fats of White Arfenic . 
Sometimes, indeed* in a Drop of the 
Water wherein Arfenic' has been boiled, I 
have difcovered a very few fingle Odtaedrs, 
confifHng of eight triangular Planes, or two 
Pyramids joined Bafe to Bafe j which un¬ 
doubtedly is the true Figure of its Cry- 
ilals, as I have fince been fully convinced 
by the Afiifiance of an ingenious Friend, 
who found Means to diffolve an Ounce 
of the white cryftalline Arfenic in about 
three Pints of Water, of which, after eva¬ 
porating a confiderable Part, he brought 
a Phial-full to me. It was then a very- 
clear and ponderous Liquor, without any 
Appearance of Cryftals: but in a few 
Days, I found the Sides of the Phial, 
even as high as the Surface of the Liquor,, 
pretty thickly covered with very mi¬ 
nute Cryftals, adhering firmly to the 
Glafs, fo as not eafily to be removed, but 
diflindt and feparate from one another. On 
examining them with Glaffes, I found them 
to be Odfaedra, uncommonly hard and in- 
foluble. After near fix Months I don’t per-; 
ceive their Size to be at all enlarged, or their 
Jsfumber to be increafed. A Drop a of the 
\ * 
a Chemifl: had prefented to him as the true Salt of Arfenic, 
and t had great Hopes by this to have gratified my Curi- 
©fity : but when I eame to try it, 1 found it abfolutely ia- 
foluble even in boiling Water, after its being reduced to 
Powder; and from its Appearance, its Hardnefs, and other 
Circumftances, X am very fufpicious it was no other tha& 
common. Spar, 
Solution* 
