214 ANNUAL OF SCIENTIFIC DISCOVERY. 



of lead, or of sulphydrate of ammonium, by means of chlorine or 

 bromine. Either of these agents readily converts oxalates into 

 carbonates by a well known reaction. The presence of an excess of 

 free acetic or succinic acid, does not prevent the complete precipita- 

 tion of manganese by peroxide of lead. The same observation applies 

 to the presence of sulphate, nitrate, and chloride of ammonium, and 

 therefore, probably to all ammoniacal salts. Salts of protoxide of iron 

 are oxidized and partially precipitated by peroxide of lead. The 

 same remark applies to the salts of cobalt. The precipitation is not 

 complete even after long digestion upon the sandbath. 



The salts of nickel and zinc are not precipitated by peroxide of 

 lead, and the nickel undergoes no higher oxidation.- Peroxide 

 of lead when perfectly free from protoxide does not precipitate baryta, 

 lime, magnesia, strontia, alumina from their solutions. The same 

 remark applies, as might be supposed, a fortiori, to the alkaline bases. 

 The application of these facts to the quantitative separation of manga- 

 nese from the above mentioned bases, with the exception of iron and 

 cobalt, is obvious. 



Dr. Gibbs then proceeds at some length to consider the several 

 cases separately. 



ROSIN OIL. 



WE derive the following facts relative to the manufacture and use 

 of rosin oil for mechanical purposes, from a report submitted to the 

 manufacturing companies of Lowell, Mass., by a committee appointed 

 to investigate the subject. Dr. Samuel L. Dana, chairman. 



The committee have considered this subject in relation to its 

 manufacture, lubricity, and economical use. Dr. Dana after carefully in- 

 vestigating the subject states as follows : -- " It was early evident to me 

 that the amount of practical information on the subject was very limited, 

 and rested on no fixed principles. I therefore devoted my time to the 

 investigation of principles relating to the process. I am satisfied, after 

 producing about 1,000 gallons, that, with due care guided by principles 

 which have been established, rosin oil of a uniform quality may be con- 

 tinuously produced at a very low rate per gallon. It was desirable, for 

 some purposes, that rosin oil should be deprived of its characteristic 

 odor without detriment. This difficult point has been completely 

 effected, and many gallons have been thus prepared, which have been 

 used by the companies. Deodorization will not probably materially 

 increase the cost of the oil. The first oily product of the distillation of 

 rosin, by a slight and cheap process, becomes applicable to all heavy 

 machinery when mixed with its bulk of sperm oil. The Merrimac 

 Manufacturing Company have used constantly, for several months, 

 this mixture on all parts of their steam engines, except the cylinder, 

 &c., on all their blowing fans, revolving at a speed of GOO or 700 turns 

 per minute, and on all the bearings in the print yard. No evil has 

 resulted from its use. It spends nearly the same as pure sperm oil. 

 It was found, moreover, _that while first run rosin oil was found per- 



