268 EARTHS. 



i/.) They contain, according to Dalton, 70 per cent, of water, 

 lose 50 by ignition ; their constitution is, according to the same 

 author, baryta 1 proportion 78, and water 20 proportions or 180, and 

 their equivalent number is 258 ; they melt in their own water, or suffer 

 the aqueous fusion ; after ignition, the dry powder which remains, 

 slacks again with great energy. 



(k.) Crystals soluble in 17J times their weight of water. 



(/.) Burning alcohol, although it does not dissolve this earth, re- 

 ceives from the crystals a yellow tinge, but this is better exhibited in 

 the flame of the compound blowpipe, in the focus of which, every 

 form of baryta, not excepting the sulphate, exhibits this characteristic 

 color in the most striking manner. 



(m.) Barytic water is a very useful reagent ; it should be kept 

 stopped from the air, otherwise it is precipitated in the form of an in- 

 soluble carbonate. It produces all the effects of the alkalies upon the 

 test colors. 



(n.) Solution of baryta forms a soap ivith oils ; its salts also form 

 soaps if mingled with aqueous solutions of alkaline soaps. 



(0.) Dust of the earth irritates the nostrils as it rises. 



4. POLARITY electro-positive, it resorts to the negative pole of 

 the galvanic battery. 



5. COMBINING WEIGHT, 78, the elements of which may be seen 

 under barium. 



BARIUM. 



1 . Obtained in the same manner as calcium, using native carbonate 

 of baryta or the pure earth,* made into a paste with water, a globule 

 of mercury being placed in a little hollow made in its surface ; the 

 paste was laid upon a platinum tray in connexion with the positive 

 wire of a galvanic battery, while the negative wire touched the mer- 

 cury. The mercury is distilled off in the same manner, but it is very 

 difficult to obtain the metal, f 



2. PROPERTIES. 



(a.} Metal of a dark grey color,'^ with less lustre than cast iron. 

 (b.) Solid at the ordinary temperature, but becomes fluid below 

 ignition. 



(c.) Near redness, rises in vapor, and acts violently on the glass. 



* Oxide of mercury may be used in obtaining the metals of the earths; one third 

 partis mixed with two thirds of the earth, and galvanized, when an amalgam is 

 formed with the metallic base. 



t Dr. Clarke states that he obtained the metal from the nitrate, by the compound 

 blowpipe. I mentioned in the memoir published in Bruce's Journal, in 1812, that 

 the metallic bases of both baryta and strontia, appeared to me to be evolved, and to 

 dart out in bright scintillations, when the earths were in the focus of the instrument, 

 but as they always burned away, I was notable to collect the metals. 



t " White color, with metallic liK-fie, having a resemblance to silver.". Murray. 



