293 CHEMICAL EXPERIMENTS. 



jr?«/«w&.--This and the two preceding experiments require 

 caution. The operator ought to be diftant during the affufion 

 of the acids, or the addition of the combuftible body, which 

 are fometimes thrown out of the verTel to a confiderable dis- 

 tance. 



7. Decompaction of fulphureous Acid Gas, by Muriate of Tin. 

 Decompofition If fulphureous acid gas, and frefli prepared muriate of tin, 

 bv murT/tfn! ^ e brought mto contact, the volume of the gas becomes fpeedily 

 diminifhed, fulphur is deposited, and the fimple muriate be- 

 comes converted into an oxigenated muriate of tin. 



8. Syrup of Violets, which has loft its Colour, regains it, when 

 agitated in Contact ivith Oxigen Gas. 



Syrup of vlakts It is a fa6t well known to chemifrs, that fyrup of violets is 

 reftored by oxi- a pt to } f e j ts co l our by age, though not the leaft perceptible 

 change in the faccharine folution has taken place, when ex-, 

 pofed to light, or even when frequently agitated in contact 

 with atmofpheric air. In order to make the difcoloured fyrup 

 regain its primitive blue colour, nothing more is neceffary than 

 to agitate it for a few minutes in contact with oxigen gas. 



9. Phofpfiorated Hidrogen Gas is decompofed by Light. 



Light decompo- Though phofphorated hidrogen gas may be kept over mer- 

 jc^phofphorated cmy in the dark for any length of time unaltered, this is not 



the cafe if the gas be expofed to light. In this fituation the 

 union of the phofphorus and hidrogen is broken, the phofpho-« 

 rus becomes feparated, and cryftallizes in the veiTel, and the 

 hidrogen is left behind. 



10. Acetite of Barites is' capable of cryjlaltizing. 



Cryftals of ace- A folution of acetite of barites, prepared by diflolving pure 



*uc or barites. k ar ;t es j n p ure ac etous acid, which had been expofed to light 



in an open glafs veiTel, was found to be converted into a folid 



regular cryftalline mafs. The form of the cryftals could not 



be determined, on account of their extreme rninutenefs. 



11. Spontaneous Reduction of Hoivard y s fulminating Mercury. 



Spcntaneous re- Four ounces of Howard's fulminating mercury were placed 

 iadiuo of ful- f t ju wet on a c halk ftone, expofed to the rays of the fun in a 

 cury# window. It was left in this fituation unobferved for at leaft 



three 



