70 Scientific Lttelligence, [July, 



margaric, and oleic acids. M. Chevreul has given this oil the name of 

 buterifij because it contains the butiric acid (or its elements), to which 

 .butter owes its odour. The other fluid substance has the properties of 

 olein. — (Ann. de Chimieet de Physique.) 



VIII. Carbonate of Magnesia in the Urinary Calculi of Herbivorous 



Animals* 



M. Lassaigne remarks, that but few of those cliemists who have 

 examined the urinary calculi of herbivorous animals have mentioned 

 carbonate of magnesia as one of their constituents; but MM. Wurser, 

 John, and Stromeyer, have discovered its existence ; the two first in 

 the urinary calculus of the horse, and the last on a calculus taken from 

 a cow. 



The results of M. Chevreul's analysis of the urine of the horse, which 

 he found to contain carbonate of magnesia, induced M. Lassaigne to 

 examine the urinary concretions of the same animal ; in which he rea- 

 dily discovered it, as well as in those of the ox and the cow. By treat- 

 ing these catcnli with sulphuric acid, sulphate of lime was principally 

 formed, but by subsequent operations magnesia was procured. The 

 quantity of carbonate of magnesia is small, forming only the 150th to 

 the 200th of the weight of the calculus. — (Ann. de Chimie etde Phys.) 



IX. Scifcty of Steam Engines. 

 M. Dupin lately read to the Academy of Sciences, the conclusion 

 of the report which he drew up in the name of a commission, to consi- 

 der the employment of low and high pressure steam-engines, princi- 

 ewith regard to the safety of the public. The commissioners were 

 , Laplace, Prony, Ampere, Girard, and Dupin. M. Gay-Lussac, 

 whose opinions differed in many respects from those adopted in the 

 Report, requested permission to withdraw from the commission. 



The recommendations adopted by the majority of the Academy 

 were : 



1. To have two safety valves adapted to the boiler; one of these 

 valves being so placed as not to be altered by the workman who has 

 the direction of the steam-engine. The other valve to be under his 

 controul, since he may have occasion to diminish the pressure, 

 whereas he would attempt in vain to increase it, because the valve 

 which he could not alter would suffer the vapour to escape. 



2. It is proposed to prove the strength of all the boilers by means of 

 the hydraulic press, by causing them to withstand a pressure four or five 

 times greater than they would be required for the usual working of the 

 machine^ as well as that this pressure should be limited to four atmo- 

 spheres. And also that the proof pressure should as many times 

 exceed that of the usual working pressure of the machine, as the latter 

 does that of the atmosphere. 



3. Every manufacturer of steam-engines should be compelled to 

 declare his method of proof, and every circumstance which would tend 

 to guarantee the solidity and safety of the machine, es])ecially of the 

 boiler and its appurtenances. The manufacturer ought also to acquaint 

 those in authority as well as the pubhc, with the pressure under which 

 these machines ought to work. 



4-. The boilora of those steam-engines which arc near any house, to 

 be surrounded with a wall, provided the engines arc sufliciently power- 



