Intelligence and Miscellaneous Articles. 235 



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The following new facts, which admit of the explanation of M. 

 Braconnot in certEiin cases, cannot I think be generalized, and that 

 other causes besides those mentioned oppose the action of acids upon 

 bases or their carbonates. 



One of the most remarkable chemical reactions is that which re- 

 sults from the contact of sulphuric acid with barytes. It is well 

 known that this combination is sometimes effected with the extri- 

 cation of so much heat, that the mass of barytes becomes red hot, 

 and part of the sulphuric acid escapes in the state of vapour. I 

 have found some peculiarities respecting this combination, which 

 appear to me to possess some scientific interest. 



A . A fragment of barytes, put into contact with cold Nordhausen 

 fuming sulphuric acid, occasioned immediate and very vivid action. 

 This action was still more vivid when anhydrous sulpliuric acid, lique- 

 fied at about 77° Fahr., was, employed. 



B. A fragment of barytes, recently calcined, put into cold sul- 

 phuric acid, containing only one atom of water, of sp. gr. 1-848, 

 suffered no alteration ; no appearance of combination occurred. 

 After remaining some time in contact, action suddenly takes place 

 when the mixture is exposed to moist air ; it may be also effected 

 by slightly touching the barytes, moistened with sulphuric acid, 

 with a hot iron, or a glass rod moistened with water. 



C. A fragment of barytes was put into contact with sulphuric 

 acid of sp. gr. 1*848, to which a small quantity of water was pre- 

 viously added, and incandescence was the immediate result. The 

 action is equally speedy when weaker sulphuric acid is employed, 

 but no incandescence occurs. 



D. Sulphuric acid of density r848, which did not act upon re- 

 cently calcined barytes, acted energetically upon barytes which had 

 absorbed a little moisture from the air. 



E. Hydrated sulphuric acid, properly diluted so as to act imme- 

 diately on barytes, does not act when cold, if it is mixed with 

 absolute alcohol or pjrroxilic spirit. 



From these different results, it may be inferred that hydrated sul- 

 phuric acid, containing only one atom of water, is with difficulty 

 separated from it ; it neutralizes in some mode the properties of the 

 acid ; for even in the presence of so powerful a base as barj'^tes, the 

 acid does not act without the assistance of heat.* 



It becomes very important to state exactly the density of sul- 

 phuric acid, when it is employed in chemical reactions ; for by the 

 experiments above detailed, it appears that this acid combines ener- 

 getically with barytes, when put into contact with this base at com- 

 mon temperatures, in the state of anhydrous acid, fuming acid, or 

 when weaker than I" 84 8, but it ceases to act when it is exactly 

 1-848. 



If the anhydrous acid, or the fuming acid of Nordhausen, did not 

 combine with barytes very energetically, it might be inferred, in 

 order to explain the necessity of weakening the acid of 1-848, that 

 the formation of sulphate of barytes cannot occur under these cir- 



* See Prof. Graham's paper on water as a constituent of salts in Lond. 

 and Edinb. Phil. Mag. vol. vi. p. 327.— Edit. 



