73t 



C O L 



Grid. ukes place very rapidly, and is accompanied with a great Pam. Reduction of TtmntrtJurt. 



> "^"Y~^*' reduction of temperature. The degree of cold obtained Sulphate of soda, til 



vane I with the acids, and even with the state of concentra- Nitrate of ammonia, .... 5 JO to '21 



olotipo of tfon in which they are employed. Lowitz has ascertained, Diluted nitroui acid 4 



* w u* * that, in the undiluted lUte. muriatic acid produces the Muriate of soda, 1 



gmtett cold, nitrous the next, and sulphuric acid the Snow, ,' 



least; the first reducing the temperature from 3'2 to Dry carbonate of ammonia, 



29, the second to 22, and the third to 11 of Snow, 



Fahrenheit. Sulphuric acid, however, when it is diluted Diluted nitrous acid, .... S t 1O 



with water, has a more powerful effect than either of the Snow, 



other two. Contrary to what we should have expected, Concentrated sulphuric acid, _ ., 



if the acids be cooled so low as to be congealed, they Snow, 



produce, when added in that state to snow, a smaller re- Muriate of soda, '2' 



duction of temperature than they produce when liquid. Muriate of ammonia, .... 1 32 to 12 



The diminution of effect is probably to be ascribed to Snow, 5 



the solution taking place more slowly. Soda crystallized, i 30 to 1 " 



A much greater degree of cold is obtained from the Snow, 



action of the salts with ice or snow, than when these sub* Potash, pure, and deprived 



stances are simply dissolved in water. A mixture of snow of its water of crystalb'za- 32 t IK 



and common <alt, reduces the thermometer to zero on tion 



the scale of Fahrenheit. As this was the greatest degree Snow 



of cold known at the time, when tint artist proposed his Concentrated acetous acid, * 3" t 17 



division of the thermometncal scale, it was conceived ,to Snow, 



be a very fit point for the commencement of the gradua- Carbonate of potash ' 3<> t 17 



tion. It has been ascertained, however, that several other Snow, 



salts have a much greater refrigerating effect, and that Nitrate of lime, ' 3 a t - 17 



ome of them produce a cold which is upwards of 70 Snow, 



below that point. The reason why the salts cause a Muriate of soda, 10 = 



greater reduction of temperature with ice or snow than Nitre .5 32 to 18 



with water, is evidently the great absorption of caloric Snow, 2t. 



which takes place during the liquefaction of the ice or Sulphuric acid diluted with) 



know, in consequence of the increased capacity in a liquid half its weight of water, j 32 to 23 



state. Snow 3. 



Having considered the various methods of producing Muriate of suda, 5 ' 



cold by liquefaction, we shall now subjoin a list of the Nitrate of ammonia, .... 5 32 to 25 



most powerful of the freezing mixtures, the materials to Snow, 1'2. 



be employed being taken by weight. Muriatic acid concentrated, 5 3 to 27 



Snow, 8 



Nitrous acid concentrated, . 4- gg to 30 



Table of Freezing Mixtures. Snow ". 



Muriate of lime 5? 32 to 4O 



Parts. Reduction of Temperature. Snow, 4 



TMe ot Muriate of Ammonia, ... 51 Muriate of lime 3 so tn in 



f"S Nitre, 5 S-from 50 to 10 Snow, 2 



Water. 16 J Muriate of lime, 5' 32 to 53 



Muriate of Ammonia, ... ~> ) Snow, : 



Nitre, 5 ( , rt Muriate of lime, 2 Q g f 



Sulphate of Soda, 8f Snow, I 



Water 16 J Muriate of lime, 3 ^Q to 73 



Nitrate of Ammonia, . . . 1 \ , n Snow, 1 



Water if Sulphuric acid diluted with 1 , () : 



Sulphate of toda, 8' - half its weight of water, J 68 to JH 



Muriatic acid 5 J Snow 8. 



Sulphate of soda, 31 



Sulphuric acid diluted with) . > 50 to 3 The mixtures in which the proportion of the ingre* 



an equal weight of water. J J dients are omitted, have been propos.-d by Lowitx: the 



Sulphate of soda 31 materials are probably meant to be employed in equal 



Nitrous acid diluted with 7 <,[ 50 to 3 quantities. 



an equal weight of water. J J The salts employed should neither be in an efflores- 



Nitrate of ammonia, .... 11 cent state, nor contain an excess of water of cry^ialliza- 



Carbonate ot suda, 1 > 50 to 7 tion ; and afu-r being reduced to powder, they should 



Water 1 J b> mixed as quickly as possible with the other materials. 



Sulphate of oda, 6~\ In thut>e mixtures in which snow is used, the snow an- 



Muriate of ammoma, . ... 4 I ewers the purpose bet when it has fallen during frosty 



Nitre, 2 > 50 to 10 weather, and is in a dry pulverulent state. In all cases, 



Diluted nitrous acid as a- 7 . I the proper proportion of the materials should be caret ul- 



.r J ly observed } an excess of any ot them is so much super- 



of suda 97 rn fluoui matter to be cooled down, and must diminish the 



acid, . . . . 4J * to ~ ** effect. 



