CHAPTER VIII. 



BAEIUM CHLORIDE — BAIUUM SULPHATE — BARIUM CARHONATE— 

 BARIUM SULPHOCARBONATE -CALCIUM OXIDE (QUICKLIME)— CAL- 

 CIUM SULPHIDE— CALCIUM CHLORIDE— CALCIUM CHLORO-HYPO- 

 CHLOKITE (BLEACHING POWDEP)— CALCIUM SULPHATE (GYPSUM 

 PLASTER OF PARIS)— CALCIUM ST'LPHITE— CALCIUM CARBIDE- 

 CALCIUM PHOSPHIDE— CALCIUM ARSENITE. 



39. Barium Chloride, BaClo. — Preparation. — By treating 

 barium carbonate (Witherite) with dilute hydrochloric acid. Carbonic 

 acid is given otf and barium chloride crystallized as small rhomboidal 

 lamella formed with two molecules of water of crystallization. 



Properties. — Barium chloride is soluble in water ; 10 gallons of 

 water dissolve 45 lb. at 15° C. Its taste is sharp. It is so poisonous 

 that 4-5 grammes, say 60-75 grains, according to Parkes, kill a man, on 

 whom it first induces general weakness, then paralysis. 



Action of Barium Ciiloride on Plants. — When plants are watered 

 with barium chloride in 0-05-0-5 per cent solution, chlorosis is in- 

 duced and lesions occur on the roots. This action is more pronounced 

 the younger the plant, and likewise varies with the nature of the- 

 plant. Barium chloride behaves like common salt and like carbonate 

 of lime. 



Action on Insects. — It appears to be very poisonous to insects. 

 Absorbed with food this salt kills them as rapidly as arsenical pre- 

 parations. 



Use against Plant Diseases. — Maravek recommends 2 per cent 

 solutions to kill injurious insects. G. Staes uses it with success against, 

 the ravagers of young beets, and especially against the altises which 

 sometimes completely devour the young leaves. Young plants support 

 a few days after sprouting a 2 per cent solution of BaCl.,, and when in 

 leaf a 3 per cent solution. Three sprayings kill coleopterous parasites. 

 Mokezecki recommends spraying with BaCl., to destroy the grub of the- 

 following ravagers : Anisoj)terix cescularia, Schiff. ; Hibernia margin- 

 aria, Bk. ; H. defoliaria, Cheimatobia brumata, L. ; Urojms ulmi, 

 Himera pennaria, Plilacetonodes sticticaUs, and Hyponomenta malinella, 

 Zell. They recommend the use of this salt according to circumstances 

 in 1^ to 2-3 per cent solution, adding 12 per cent of sodium carbon- 

 ate to give adherence to the liquor by the resulting barium carbonate. 

 The action of this product on the grubs makes itself felt after four 

 hours, whilst emerald green under similar conditions requires twenty- 

 four hours to act. This poison, very violent to grubs and insects, would 

 appear to be harmless to the plants treated, for neither the leaves nor 

 the fruit appear to suffer in contact. It is, however, costly and very 

 (138) 



