Intelligence and Miscellaneous J r tides. 317 



bad conductors of heat, — and their external parts are the first heated, 

 — the dilatation which they suffer forces them to separate from the 

 neighbouring parts which have not yet acquired the same tempera- 

 ture, and this is facilitated by their property of cleaving. 



Tliere are substances which may decompose and yieki volatile pro- 

 ducts when heated, and in this case it is difficult to say whether it is 

 to an unequal dilatation of their parts or to the repulsive action of 

 these volatile products that the decrepitation is to be attributed. 

 However, as they possess almost all a crystalline structure or an easy 

 cleavage, this structure is probably often the only cause, for they de- 

 crepitate actually without having suffered the least apparent decompo- 

 sition, as the cyanide of mercury and emetic tartar. Substances which 

 do not possess a crystalline structure, may decrepitate when they have 

 not been perfectly dried ; such are plastic clays and argillaceous schist. 



From what has been staled, decrepitating substances may be di- 

 vided into two classes, viz. fixed bodies, and those which yield aeriform 

 products. Among the first are sulphate of barytes, sulphate of stron- 

 tian, sulphate of potash, chromate of potash, bichromate of potash, 

 fluoride of calcium, chloride of sodium, chloride of potassium, bro- 

 mide of sodium, bromide of potassium, iodide of potassium, and 

 galena. Of the bodies which decompose and yield aeriform products 

 at a high temperature, some are anhydrous, as nitrate of barytes, 

 nitrate of lead, rhombic carbonate of lime, and cyanide of mercury. 

 Others are hydrates, as tartar emetic, lamellar sulphate of lime, ace- 

 late of copper, bitartrate of potash, and ferrocyanide of potassium. 



Those substances which contain a large quantity of water in a state 

 of combination do not really decrepitate, unless they are susceptible of 

 cleavage : such are the carbonate of soda, sulphate of soda, sulphate 

 of magnesia, &c. 



Cleavage therefore is as essential a condition of decrepitation as 

 water or its elements. — Journal de Pharmaeie, July 1836. 



ATOMIC CONFUSION. — MONOUYDRATED SULPHOCARBETHERIC 

 ACID. 



The above title is suggested by the perusal of a paper in 

 the Journal de Chimie Medicale, July 1836, entitled, " Sur un Me- 

 moire dc M. Coucrbe sur la Chimie du Sulfure de Carbon," 

 "M.Zeise, on examining the reaction of sulphuret of carbon and pot- 

 ash dissolved in alcohol, obtained a crystallized salt which appeared 

 to be formed of potash and a hydracid equivalent to hydrogen, and a 

 sulphuret of carbon which he regarded as very probably different, 

 in the proportion of its elements, from the sulphuret of carbon of 

 Lampadius. There was then, according to M. Zeise, a sulphuret 

 of carbon, which acted the part of a complex supporter of combus- 

 tion {comhurnnt complcxe), resembling cyanogen. In consequence 

 of this analogy, M. Zeisc called this sulphuret xanthogcn (on account 

 of the yellow colour of several of its compounds with metals). Its 

 hydracid he named hydroxanlhic acid, and its compounds with me- 

 tals he called xantlmrcts. He considered the oily liquid derived from 

 the reaction of sulphuric, hydrochloric, or acetic acid on his cry- 

 stallized salt as hijdroxanthic r/aV/, and the precipitates derived from 



