1«15.J Scientific Intelligence. I57 



of England and France, to express temperature in future in none 

 but centigrade degrees, v\k)uM quickly become general, and form 

 an universal language in this respect, to the expulsion of Fahren- 

 heit's ridiculous scale, as well as the others, which occasion such 

 unnecessary delay and difficulty in fixing the different degrees of 

 heat in the memory, when running through chemical experiments 

 in both the languages. 



I may also perhaps be permitted to mention, to those who are 

 making experiments on the conversion of starch into sugar, by 

 Kirchoff's method, that if the boiling be performed by passing 

 steam into the fluid, all risk of empyreuma may be avoided, desic- 

 cation ])revented, (as the volume will continue any length of time 

 nearly the same,) and the operation can be performed in porcelain, 

 eartiien ware, or even wood vessels. 



Mr. Wilkinson, the celebrated Iron-master, could not produce 

 any current of air through cast-iron pipes, (extending about a mile 

 in'length,) even to the distance of 600 feet from the impelling 

 force, which was very great ,• yet the gas-light companies find no 

 difficulty in this respect, — May I request an explanation of this 

 anomaly from any of your correspondents ? 1. H. 



XII. Formation of Sal-Ammo7iiac in burning Bricks. 



(To Dr. Thomson.) 

 SIR, 



In your Sketch of the latest Improvements in the Physical 

 Sciences, under the division Salts, article Sal-ammoniac, you ob- 

 serve, " that the sand employed in making bricks probably con- 

 tains common salt, derived from the sea water with which it is 

 washed ; and that this may be the source of the muriatic acid, 

 which goes to the formation of the sal-ammoniac that sublimes 

 during the burning of the bricks ; but that if this be the case, 

 nature employs, during this process, some method of decomposing 

 common salt, at present unknown to manufacturers, &c." 



In reply to this observation, 1 beg leave to remark, that as sul- 

 phate of ammonia generally accompanies the volatile products of 

 burning co:i!s, it is not improbable that this salt dccompuecs the 

 common salt that adheres to the sand, and gives rise to the pro- 

 duction of the muriate of ammonia in question. 



1 shall l)c much obliged to you to inform me, of some practicable 

 method of separating manganese when In solution from the sola- 

 tlon of a neutral salt. A minute portion of this metal communi- 

 cates a pi rniancnt stain to a coiisidcraLle quantity of any neutral 

 .xulphate that may happen to contain it. 



1 remain, Sir, your most humble servant, 



UrUtvl, Jan. 14, ISl.'i. E, T f 



