DISTILLATION, 



755 



the Scotch stills, as much as 160 gallons is drawn from 

 a 500 gallons still in 20 minutes. Supposing one-third 

 of this product to be spirit and the rest water, the spi- 

 rit would require an expenditure of 26 lb. of the best 

 Newcastle coal, and the water 107 lb. ; making 133 lb. 

 or nearly 1^ bushels of coal. This is more by half a 

 bushel than is consumed by a steam engine of 40 

 horse power. The means of condensation in a process 

 so rapid must have been also very great. The vapour 

 of the 53 gallons of spirit, during its condensation, 

 would raise the temperature of 340 gallons of water at 

 50° to 120°, while the vapour of the 107 gallons of 

 water would raise 1440 gallons of cold water through 

 the same range of temperature. The total supply of 

 cold water in 20 minutes would, therefore, be 1547 

 gallons, or 77-3 gallons in one minute. 



When the distillation is very rapid, as in the instance 

 above alluded to, the wash, or fermented wort, from 

 which the spirit is drawn, abounds with so large a 

 quantity of mucilage, and other vegetable matter, that 

 it is very liable to deposition. This matter is apt to 

 burn on the bottom of the still, producing an empyreu- 

 ma, which gives a disagreeable flavour to the spirit. 

 This evil, however, is in a great degree obviated by a 

 piece of machinery, which works in the still by a mo- 

 tion communicated from the outside. It consists of a 

 rake, which is constantly turning in contact with the 

 bottom of the still. In the first distillation from the 

 wash, in which about one-third of the whole is drawn 

 off, this apparatus is absolutely necessary. This pro- 

 duct is called singleings. This last undergoes a second 

 distillation, from which about one-third of the whole is 

 drawn. In this stage, it will be evident, that the ma- 

 chinery for raking the bottom will be unnecessary. 



In the second distillation it will be proper to remark, 

 that, in consequence of the distilled product being al- 

 most wholly spirit, the means both of evaporation and 

 condensation will require to be less. The quantity of 

 caloric required to raise water into vapour, is about 

 1 lb. of coal for every gallon of water. The latter will 

 then require about 13 gallons of water at 50° to con- 

 dense it, and reduce it to the temperature of 120°. 

 The same quantity of heat will raise a little more than 

 double the quantity of pure spirit into vapour. The 

 same fuel and cold water, therefore, which would be 

 expended on one gallon of water in its distillation, 

 would distil more than two gallons of spirit. Count 

 Rumford has lately ascertained, that the quantities of 

 heat required to raise water and alcohol into vapour, 

 are something more than 2 to 1 ; and he is of opinion, 

 that ether requires about one-half the quantity of heat 

 with that of alcohol. Hence we should conclude, that 

 the means of evaporation and condensation for water 

 will be four times that required for ether. 



Besides the alcohol, which comes over with greater 

 facility than the water, there are other volatile matters 

 which are furnished by the vegetable substance from 

 which the fermented liquor is procured. These are 

 essential oils, which are different in the different fer- 

 mented liquors. When they are from wine, or from 

 the wash made from sugar, their aroma is rather of an 

 agreeable flavour, and the rectifier becomes less anxious 

 about their separation. Those essential oils which are 

 afforded by the wash made from malt, or other grain, 

 are very disagreeable to the smell ; and, in this case, 

 the purification of the spirit has long been "a desirable 

 object to the rectifier. 



The rectifier buys his spirit from the distiller, in the 

 state of what is called raw spirit. This generally abounds 



with all the impurities which are volatile, little or no Distilia- 

 pains being taken to purify the spirit in the first pro- 'i ** 

 cess. Every rectifier has his secret for purifying his *""^~V"^" 

 spirit. It very often happens, however, that, instead 

 of removing the offensive aroma, he substitutes one 

 which overpowers and disguises the original. This is 

 mostly the case in the different kinds of gin, and other 

 compound cordials. In some instances, when the spi- 

 rit is very weak, and the essential oils are abundant, 

 the water exerts a greater attraction for the alcohol 

 than that of the alcohol for the oil ; by which means 

 the oil becomes free in the liquid, giving it a turbid 

 and milky appearance. In this case, the separation of 

 the oil becomes an object. It is common to add alka^ 

 lies for the purpose, forming saponaceous compounds 

 with the oil, by which it acquires a greater degree of 

 purity, and is less liable to rise in the rectification, 

 which consists in distilling with a moderate heat. Acids 

 have the property of converting essential oils into resi- 

 nous substances, by which they become less volatile, 

 and are, in consequence, easier to separate from the al- 

 cohol by distillation with a low heat. The rectifier, 

 employs a distilling apparatus similar to the distiller in 

 every respect, but he proceeds with more care in the 

 application of his heat. 



In the distillation of water, so constantly required in Distillatioi 

 medicine and in the laboratory of the chemist, much °f water. 

 more precaution is found necessary than was former- 

 ly thought to be the case. The impropriety of distil- 

 ling river waters, or others liable to contain animal and 

 vegetable matter, it will be needless to point out, as it 

 is well known that such distilled water is liable to pu- 

 trefaction. The water to be distilled should be the 

 most complete spring water, taken from some place 

 where it has not run over any vegetable soil. If it con- 

 tain muriate of lime, or any other very deliquescent salt, 

 these salts are found to rise with the water, and never 

 fail to exist in the distilled water. When the water to 

 be distilled contains muriate of lime, the addition of a 

 little soda decomposes the salt, producing muriate of 

 soda and lime, neither of which will rise in distillation. 

 It is owing to the presence of the muriate of lime in 

 sea water, that has rendered it so difficult to purify it 

 by distillation. 



The distillation of what is called crude ammonia, or 

 hartshorn, is carried on upon a large scale in several 

 parts of the kingdom. The materials to be distilled 

 are in general bones and hoofs of animals. On some 

 occasions urine is used for the same purpose. 



In the distillation of bones, an iron still is generally Distillation 

 used, with a pipe leading from it, connected with a »f bonei. 

 worm tub, similar to that already described. The 

 vessel being filled with bones roughly broken, a strong 

 heat is applied. Water and animal tar first come over, 

 accompanied by a very fetid inflammable gas : Carbonic 

 acid gas also comes over, but the latter is mostly taken 

 up by the ammonia, which is also formed at the same 

 time. These come over into the receiver in the state 

 of carbonate of ammonia. When the different sub- 

 stances have heen condensed in the worm, they should 

 pass into a receiver, which has no communication with 

 the open air. This would not only render it almost 

 impossible to exist in the same place, but would consti- 

 tute a nuisance in the vicinity of any town. 



The receiver should have no opening outwards, but 

 through a pipe inserted into the upper part of it, and 

 connected with the fire of the still. The inflammable 

 gas and the smell are conveyed to the fire, where the 

 former takes fire ajad burns. It may be proper here to 



