httelligeiice and Miscellaneous Articles. 221 



then to be exposed to a temperature of about 68°, till nearly all the 

 alcohol is converted into acetic acid. 



Fresh air is to be occasionally admitted into the balloon, and care 

 taken that the liquid is always below the pumice, and that the latter 

 is never covered by the former. In about a fortnight or three weeks 

 the liquid becomes more or less viscid, its consistence resembling 

 that of sulphuric acid on being poured. At this period the liquid is 

 to be removed, and replaced by an equal quantity of alcohol of 60 

 per cent. When several pints of very acid liquid have been thus 

 obtained, it is to be 'neutralized by carbonate of potash, and as much 

 chloride of calcium dissolved in it as it is capable of taking up. 

 Dried acetate of potash may be substituted for chloride of calcium ; 

 in this case it is unnecessary to saturate the liquid by the carbonate 

 of the same base. 



In whatever mode the liquor is saturated, it is to be submitted to 

 cautious distillation ; only one-fourth of it is to be distilled, and in a 

 well-cooled receiver ; this is to be saturated with fused chloride of 

 calcium, which immediately separates a considerable portion of a 

 very volatile fluid of an extremely suffocating odour ; this is to be 

 separated by a pipette, and water is to be cautiously added to the 

 saline solution as long as it continues to separate fresh quantities of 

 sethereal fluid, which is to be added to that previously obtained. By 

 careful distillation of the solution of chloride of calcium, a still 

 further small portion of the organic matter may be extracted : as 

 already remarked by M. Liebig, the substance thus separated is a 

 mixture of aldehyd, acetic aether, alcohol and acetal. 



In order to isolate the acetal, powdered chloride of calcium is to 

 be added to the mixed fluids, as long as it continues to dissolve ; 

 when this is completed, the liquid is to be distilled from a water- 

 bath, but always below its boiling-point, until the product ceases 

 to reduce ammoniacal acetate of silver. The residual matter, de- 

 prived of aldehyd, but still containing some acetic aether and al- 

 cohol mixed with the acetal, is added to a great excess of very con- 

 centrated solution of potash, which completely destroys the acetic 

 aether : in operating upon about 750 grains of the fluid, and very 

 frequently agitating the mixture, it requires three or four days' action 

 to decompose the last portion of the aether. It now remains only to 

 wash the acetal with once or twice its volume of water, to digest it 

 with recently-fused chloride of calcium, and to distil it, in order to 

 have it perfectly pure. 



The properties of acetal are, that it is a colourless aethereal and 

 fluid liquid, but less so than aether, to which it has been compared. 

 It has a peculiar sweet smell ; its taste is cooling with a distinct nutty 

 after-taste. Its density is 0'821, at about 72° F. It boils between 

 219° and 223° F. Water at 77° dissolves about ^th of its volume, 

 and less as its temperature is increased. Chloride of calcium and all 

 very soluble salts in general separate the acetal from solution in 

 water ; Ktlier and alcohol dissolve acetal in all proportions ; chloride 

 of calcium does not separate it from alcohol unless water be added ; 

 aldehyd. as observed by M. Liebig, exhibits the same phaenomenon. 



