422 Scientific Intelligence. 
the proper temperature, the relative amount of blast to the rigs 
operated upon should be carefully vomited. If too mar the process 
goes on slowly, and much heat is lost by radiation; on the other hand, if 
too much blast is used, there is also a loss from the heat carried off by 
the air which is forced ae the iron before it has —_— the desired 
mposition. The pressure of the blast must, at all events, be greater 
than that of the column of i iron in the furnace, in order ‘that the bath of 
molten iron shall be are 1nd penetrated and the whcle melted mass 
- violent agitation, In Sweden the pressure of half an atmosphere 
n most cases been found sufficient, while i in England a pressure equ 
‘to ib atmospheres has been used. 
Tunner places ene oy emphasis on the employment of a ae pret: 
a thee hot bi He says that if the blast were to be heated to 
, or geen even to 500-600° C., the pee would un- 
questionsbly ‘proceed with great regularity and completeness, and the dif 
feu Ities e manufacture of soft bar-iron and steel would be overcome. 
ssc it is to be borne in mind, bhakti in order to produce a given va 
riety of steel or iron, the process of conversion must be inter rupted — 
ever the refining has reached the desired point; this last is determi 
by observing the character of the gases and sparks which escape ~ 
The cost for furnace cpa: ne less than: was at first gore but Be 
when the jron | is a 
sepmderation the length of time that has been necessary to nee the 
ess has accomplis shed so much in so han a time, we have vig 
to hope that the day is ies far distant when the still rema’ 
difficulties in this Pp e853 ill a minimum.—?' 
nisches Journal, clxvi, 447. [A wide field is open for the application 9 in 
_ Bessemer’s pone in this. country, where pure iron ores, fully equ’ 7 
Sangh to those of Sweden and Norway, occur in such abundan 
