ARTESIAN WELL 221 



and continue the boiling ; if the copper becomes now either steel-grey, blue, or black, 

 I remove it, and wash it free of grease in another vessel in which there is hot diluted 

 hydrochloric acid ; I now dry it, and, with a scraper with a fine edge, take off tho 

 deposit with some of tho adhering copper, and repeat the boiling, washing and scraping, 

 so as to have four or five specimens on copper ; one of these is sealed up hermetically 

 in a tube for future production. I now take a piece of glass g 



tube, and having heated it in the middle, draw it out, as in 

 fg. 86, dividing it at A, each section being about 2 inches 

 long, the wide orifices being about ^gths of an inch in dia- 

 meter, and J an inch long, the capillary part th of an inch in 

 diameter and 1 inch long ; now, by putting one portion of B 



the scrapings into one of the tubes at B, and holding it upwards over a very small 

 flame, so that the volatile products may slowly ascend into the narrow portion 

 of the tube, wo prove tho nature of the deposit : if mercury, it condenses in minute 

 white shining globules ; if lead or bismuth, it does not rise, but melts into a yel- 

 lowish glass, which adheres to the copper ; if tellurium, it would fall as a white 

 amorphous powder ; if antimony, it would not rise at that low temperature ; but ar- 

 senious acid condenses as minute octahedral crystals, looking with the microscope like 

 very transparent grains of sand. I make three such sublimates, ono of which is 

 sealed up like the arsenic for future production. I now cut the capillary part of 

 another of tho tubes in pieces, and boil it in a few drops (say 10) of distilled water, 

 and when cold drop three or four drops on a plate of white porcelain, and with a glass 

 rod drop ono drop of ammoniacal sulphate of copper in it : and now to make the 

 colours from this and the next test more conspicuous, I keep a chalk-stone, planed 

 and cleaned, in readiness, and placing on it a bit of clean white filtering paper, I con- 

 duct the drops of copper-test upon the paper, which permits the excess of copper-solu- 

 tion to pass through into the chalk, but retains the smallest proportion of Scheele's 

 green ; the other few drops of the solution are treated the same way with the am- 

 moniacal nitrate of silver. "When I get the yellow precipitate of arsenito of silver, 

 the papers, with these two spots, are now dried and sealed up in a tube as before, 

 and that with the silver must bo kept in the dark, or it will become black. I have 

 still ono of the tubes with the arsenical sublimate remaining ; through this I direct 

 a stream of hydrosulphuric acid gas for a few seconds, which converts the sublimate 

 into yellow orpiment. I have now all five tests r the metal, tho acid, arsenite of cop- 

 per, arsenite of silver, and yellow sulphuret ; and the ^ O o 000 fa of a grain of arsenic 

 is sufficient in adroit hands to produce the whole ; but all five must be present, or 

 there is no positive proof, for many matters will cause a darkness of the copper in the 

 absence of arsenic, sulphurets even from putrefaction ; but there is no sublimate in 

 the second operation, because the sulphur burns into sulphurous acid and passes off 

 upwards. Corn, grasses, and earth slightly darken it from some unknown cause, but 

 produce no sublimate ; so, if tho solution of suspected arsenious acid is tested with 

 the copper-test while hot, it will produce a greenish deposit of oxide of copper, through 

 tho heat dissipating a little ammonia, or if tho copper blade has not been deprived of 

 grease by tho diluted hydrochloric acid, the sublimed acid from the grease will pre- 

 cipitate copper from that test ; but as much of tho sulphuric acid of commerce, and 

 nearly all such hydrochloric acid and some commercial zinc contains arsenic, nothing 

 can excuse a toxicologist who attempts to try for arsenic if he has not previously ex- 

 perimented with all his reagents before he introduces the suspected matters. I 

 should also mention that this metal is to be found in all parts of the body, but longest, 

 and in greatest quantity, in the liver, where it is frequently found many days after it 

 has disappeared from the intestines.' W, Herapath. 



Arsenious acid of commerce is frequently adulterated with chalk or plaster of 

 Paris. These impurities are very easily detected, and their proportions estimated. 

 Arsenious acid is entirely volatilised by heat, consequently it is sufficient to expose 

 a weighed quantity of the substance to a temperature of about 400 F. in a capsule or 

 crucible. The whole of the arsenic will pass off in fumes, while the impurities will 

 be left behind as a fixed residuum, which can, upon cooling, be weighed. 



The mines of Cornwall and Devonshire produced in 1871, 4,147 tons, 15 cwt. of 

 arsenic, the value of which was 15,5191. 18s.; a considerable quantity is also produced 

 at Swansea, from the roasting of arsenical copper ores. 



ARSIUE. A name used by some modern chemists for arseniuretted hydrogen. 



ARTESIAN WELIi. This is a description of well or borehole in which 

 water is obtained by means of a perforation bored vertically down through imperme- 

 able strata to an underlying stratum of a more or less permeable character, such 

 stratum to bo charged with water and to exist either in the shape of a basin-shaped 

 depression, or to be so inclined as to reach, at some distance from the point at which 

 the borehole may bo made, the surface of the earth. Tho name is derived from tho 



