Chemistry and Physics. 131 
more. There is, to be sure, no royal road to learning, but there is a 
least difficult and tolerable way, and this is well PP ov rth looking 
ho 
the laboratory. The book is not a reduction of some standard 
treatise executed to order for a publisher’s “series,” ae is the work 
of accomplished chemists and successful teachers, a judicious 
selection and presentation of facts, the book i is highly “axtlethotory. 
nf ature, however, is its instructions for ex erimenting. 
There have not ca gies ~ attem nts in the same direction, — 
and all of which are ae certain of turning abteentallg and 
instructively, by reason of the appropriate minuteness with which 
the conditions of success are detailed. 
As regards the development of “ modern” an eee not aly ec 
has been attempted and in our opinion this is we es ern’ 
atomic weights are pho gto "The laws and consequences of com- 
tion by volum digg sd 
sse 
a cusierentie yet preciative point of The 
basia of facts and ‘established 
heartily commend this book to all teachers and students of chem- 
istry as the rs we are acquainted with for really pees the 
bere of the science. 
se re eis é of 5 whet the metals Molybdenum ‘an | Chro- 
ee oveHuin, M.D, (Communicated for this 
Tourn). > Mol sods, was first prepared by Hjelm in the year 
pve His method consisted in wrens’ oe trioxyd of mo 
“enum in @ porcelain crucible for 2 or everal je er 
methods have since been used, prominent fovea iy sein being that 
of heating the acid molybdate of potassium ; also the reduction of 
molybdate of ammon um by heat, or the reduction of trioxyd of 
molybdenum by machanaty of soda. Mo olybdenum is described 
a8 a silver-white metal, not altered by contact with air at ordin 
ueetature. Sp. gr. 85; not attacked by Sinneaan acid or 
ute sulphuric acid. St trong sulphuric and nitric acid on the con- 
act very powerfully upon it with evolution of sulphurous acid 
and hyponitric acid. Ha: ving had occasion during June, 1867, to 
all very, molybdenum, I tried the methods above stated; they were 
. y e 
 .. to Fresenius, page 179 and 180, Qualitative Analysis. 
Thoneng (a, Eresenins 
