FREETOCAtf. 



FREEZING APPARATUS. 



Ood the creator of the universe U omniscient. To him time put, 

 prevent. n<l future, is one. We conceive him u knowing all tiling, 

 willing *11 thingi, directing all thing*. But our acts of free-will then, 

 it may be urged, are God* will, and therefore not nun'*. Then-tote 

 free-will in man in any sense contradict* our notion of God's power. 

 To thin we aniwer, that man's power to will U here considered a* a fact 

 of which our daily experience convince* u*; and further, that the 

 existence of this power is a legitimate deduction from the nature of 

 man's mind, which is here supposed to have an activity independent 

 of all sensuous impression*. It U admitted that if our actions are 

 viewed in reference to the power of Ood, as we conceive it, we cannot 

 r(xmrito our notion of the freedom of our action* with our notion of 

 the power of Qod. But there U no contradiction here. Contradiction 

 implies that the things between which it arise* are equally within the 

 cognisance of our understanding. It is no contradiction to say that 

 Qod wills all men's acts, and that man wills his own. Both things 

 may be true, though we cannot comprehend how it is so. 



KKKKDMAN. [Suv*] 



FREEMAN. [MUNICIPAL ConponATiOKS.] 



FREESTONE. A term applied by practical masons to those de- 

 scriptions of building stones which are able to be worked with the 

 ordinary mallet and chisel, in contradistinction to those which arc 

 worked by the pick, or which it is necessary to stun. The various 

 descriptions of oolites, sandstones, limestones, and the softer kinds of 

 grits, are classed as frtatonet, and they may all be sawn, either by the 

 piste or by the toothed raw ; the granites, the millstone grits, the 

 burrs, and the lavas or basalts, are not included in this class : nor are 

 the slate rocks, though they are capable of being sawn by the plate 

 saw. In fact the term freestone is only applied to those materials 

 which are susceptible of easy conversion to the ordinary purposes of 

 building, and the distinctly marked cleavage of the slate rocks renders 

 this operation almost impossible in their cases. 



FKEE/ING U the solidification of fluid bodies by the abstraction of 

 the heat necessary to their fluid form. It occurs by the effect of 

 natural cold in many liquids ; and moat of them may be frozen by an 

 artificial reduction of temperature. It is to be observed, that what 

 are termed the fretting points vary greatly in different fluids, and their 

 remaining such at different temperatures depends upon the different 

 degrees of power with which they retain the heat necessary to fluidity. 

 Liquids may be considered an solids in combination with heat, which 

 exists in them in a latent state, and which they give out as sensible 

 hi-.it when they return to the solid form. 



In passing into the solid state, certain liquids undergo a sudden and 

 often considerable change of volume, which may either be an enlarge- 

 ment or a diminution. For example, when mercury is cooled to 39 

 Fahr.,agreat and sudden contraction takes place; so much so, that 

 when observed in a thermometer, it falls through a considerable num- 

 ber of degrees, and the whole of it may retire into the bulb. The 

 reverse of this takes place in the case of water. In passing from 3S'S 

 to 32, its freezing point, it undergoes a regular expansion ; and in 

 puling into the solid state it undergoes a further expansion, amounting 

 to one-seventh of its bulk. And so irresistible is this expansion, that 

 rock* are rent asunder by the freezing of water in their crevices; vessels 

 and pipes containing water are burst ; and it was calculated, in the case 

 of a strong brass globe, filled with water and closed by a screw, and 

 burst by the freezing of the water within it, that the force necessary to 

 produce this effect amounted to not less thaii 28,000 Ibs. When liquid 

 phosphorus is gradually cooled it regularly contracts ; and, passing into 

 the solid state at about 100, it undergoes a sudden and considerable 

 contraction. The same observation applies generally to oils in the pro- 

 cess of freezing, and it has been remarked that, in general, bodies which 

 do not crystallise in freezing undergo a sudden contraction, while those 

 which do so crystallise undergo a sudden expansion. Sulphuric acid, 

 however, in becoming solid, or passing from the solid into the liquid 

 state, does not appear to suffer any change in volume. Cast iron, bis- 

 muth, and antimony expand in solidifying ; the other metals, however, 

 contract in doing so. 



What are called frteiing mixture* are such as produce cold by and 

 during the liquefaction of their solid ingredient, and the consequent 

 absorption of the heat on which its solid form depended. Such mix- 

 ture* reduce the temperature of substances immersed in them on the 

 principle of the transfer of heat, which always takes place from hotter 

 to colder bodies when exposed to each other. 



The process used by confectioner* for producing cold is by the mix- 

 ture of ice and common salt, which, both liquefying, absorb so much 

 heat, or in other words produce as much cold as will reduce the ther- 

 mometer from the usual temperature to the zero of Fahrenheit's scale, 

 or even rather below it. If, however, freshly fallen snow be used 

 instead of ice, then the fluidity is more suddenly produced and the 

 cold is more intense. 



In freezing mixtures, the substances combined have such an affinity 

 for each other that when intimately blended they combine chemically, 

 and in doing so liquefy. The operation should be so arranged that no 

 beat be furnished either by the vessel in which the liquefaction takes 

 place, or from any external source. Under such circumstances, the 

 heat absorbed during the liquefaction must be furnished by the 

 materials of the freezing mixture (in which case the reduction of 

 temperature will be proportioii.il to the quantity of heat 



latent), or by the body which it U Intended artificially to cool or 



t . Ir. H 



The reader will find in works on chemistry many recipes for freezing 

 mixtures. One or two examples will suffice here. With equal weight* 

 of fresh mow (or pounded ice) and common salt a temperature of 

 4* Fahr. can be maintained for many hour*. A mixture of three 

 part* crystallised chloride of calcium ana two part* of snow will pro- 

 duce a depression of temperature sufficient to freeze mercury. If the 

 vessel in which the materials are to be mixed and the chloride be 

 cooled to 32, a temperature of 50* can be produced. The most 

 powerful freezing mixture is formed by dissolving solid carbonic acid 

 or solid nitrous oxide in sulphuric ether. In this way temperatures of 

 120 to 148 have been obtained, at which alcohol passed from th 

 consistency of oil to that of melting wax. For more moderate tempe- 

 ratures, certain salts easily procurable may be used. Thus, 4 ozs. of 

 nitre and 4 ozs. of sal ammoniac, both in fine powder, mixed with 

 8 ozs. of water, will reduce the thermometer from 50 to 10. Kqual 

 parts of water, of powdered crystallised nitrate of ammonia, and of 

 powdered crystallised carbonate of soda, will lower the temperature 

 from 50 to 7. 



FREEZING APPARATUS. The first apparatus of thi* kit. 

 an air-pump contrived by Sir John Leslie for the purpose of freezing 

 liquids in vacuo. 



It is well known that liquids evaporate more readily when the 

 atmosphere is removed from their surfaces than when they are subject 

 to its pressure ; the caloric producing the evaporation being that wliirh 

 exists in the liquid itself, and that which, in consequence of the dis- 

 turbance of the equilibrium, enters the liquid from the neighbouring 

 bodies : hence, if there be a quantity of sulphuric ether in a vessel 

 under the receiver of an air-pump, and in it there be placed a vessel or 

 tube containing a small quantity of water, on exhausting the receiver 

 the ether will rapidly evaporate, and, the operation of exhausting 

 continued, the vapour will be carried off as fast as it is formed. The 

 caloric in the water is withdrawn at the same time, and at length tin- 

 water is converted into ice. 



In order to produce the congelation of water by a rapid evaporation 

 from its own surface under the exhausted receiver of an air 

 Leslie introduced into the receiver a shallow vessel containing < 

 concentrated sulphuric acid, above which was placed the ves 

 taining the water. The air being extracted as quickly as possible, the 

 vapour which, in consequence of the removal of the pressure, escaped 

 continually from the water, even at the medium temperatmv of tin- 

 atmosphere was, by the strong attraction of the acid for it, nl 

 as fast as it rose ; and in two or three minutes the quantity withdraw n 

 from the water was sufficient to allow a congelation of the water to 

 take place. Instead of sulphuric acid, any substance which (as dry 

 potash, muriate of lime, or calcined powder of basalt) has a 

 attraction for humidity may be used ; but the first, if highly concen- 

 trated, is the most efficacious. 



The air-pump employed for the purpose by Leslie was const i 

 in the usual manner, but of large dimensions, in order to obtain 

 considerable quantities, and the receiver was a segment less than a 

 hemisphere, that the air contained in it might be extracted as speedily 

 as possible. The sulphuric acid or absorbent earth was contain, 

 shallow vessel of glass, nearly equal in diameter to the base of the 

 receiver ; and from the centre of the vessel rose a hollow cylinder, mi 

 the top of which, above the acid or earth, rested the cup of glass, or 

 rather of unglazed earthenware, which contained the water to bo 

 frozen. Machines of this kind have been varied in different ways, the 

 last and most successful of which produced great blocks of ice by the 

 evaporation of ether, and the process of welding slabs of ice as fast as 

 they were formed. The ether was conducted into a separate chamber 

 and condensed, so that it could be used over and over again with little 

 or no loss. This apparatus was patented by Mr. Harrison, " for pro- 

 ducing cold by the evaporation of volatile liquids in vacuo, tin 

 densation of their vapours by pressure, and the continued re-evapora- 

 tioii and re-condensation of the same materials." A detailed account 

 of this apparatus with diagrams, is given in the ' Pharmaceutical 

 Journal,' xvi, 477, but we may state briefly that the apparatus consist* 

 first of an air-tight metallic vessel, from which air is remove! 

 pump, and in which ether is kept constantly evaporating; secondly, of 

 an air-tight metallic vessel, into which the ether vapour as it 

 moved from the former vessel is condensed under pressure ; thirdly, of 

 a pump, by which the vapour of the evaporating ether is withdraw n 

 from the first vessel and forced into the second, where, as the pressure 

 increases, it assume* the liquid state ready to be again evaporated. 

 Thus the process is continuous, and there is no appreciable loss. The 

 first and second vessels are surrounded by water, and the cold 

 by the rapid evaporation of the ether in the former vessel can 

 water surrounding that vessel to freeze, while there is, of course, a 

 corresponding elevation of temperature in the water which surrounds 

 the other vessel where condensation takes place. The only expense U 

 said to be for motive power, which is supplied by a steam-engine of 

 10-horse power, and it is stated that 1 ton of cool economically n\ 

 is equal to the production of 4 tons of ice. The apparatus was 

 bited in London in the summer of 1858, and is now, we belii 

 Australia. 



Leslie, by means of the like apparatus, succeeded in freezing mer- 



