May I, 19 19] 



NATURE 



169 



steel. It is produced only when the latter cools 

 down and has partly solidified. Steel that will 

 produce blowholes contains in the molten condi- 

 tion dissolved carbon and oxygen, and for each 

 temperature and composition there is a particular 

 equilibrium at which no chemical reaction takes 

 place. The heat is then what is called "dead- 

 melted." If, on one hand, the temperature 

 is raised, the reducing- action of the carbon is 

 intensified, and carbon monoxide will be evolved ; 

 if, on the other, the temperature is lowered, 

 nothing happens until the steel has partially 

 solidified. This causes an increased concentration 

 of carbon and oxygen in the still liquid portion, 

 as a result of which carbon monoxide is evolved. 

 This gas is unable to escape, and by its pressure 

 produces the blowholes. On cooling, it is gradu- 

 ally absorbed by the now solid metal. 



As yet almost nothing is known as to the con- 

 dition in which these gases exist in metals and 

 alloys. Prof. McBain pointed out in his con- 

 tribution to the discussion that the occlusion of 

 gases by metals comprises processes which are 

 special instances of the general group of different 

 phenomena known collectively as "sorption," and 

 that in the vast majority of cases the intermingling 

 phenomena have not been disentangled or even 

 5 experimentally identified. It is necessary to take 



into consideration true adsorption (surface con- 

 densation), true absorption (true solution in a 

 solid), and chemical reactions that may ensue. 



Sir Robert Hadfield finally considers briefly the 

 methods which have been found effective in pro- 

 ducing sound steel. As he points out, great diffi- 

 culties were experienced in the early days of 

 making steel castings in producing sound metal. 

 The very useful element silicon was scarcely ob- 

 tainable except in combinations which caused as 

 much trouble as the unsoundness itself. High- 

 percentage ferro-silicons with low carbon and 

 silico-speigels were unknown. Manganese, though 

 useful, was only a partial cure, and aluminium 

 as a commercial metal had not yet arrived. 



It appears that it was three French metallurgists 

 who introduced and perfected the successful pro- 

 duction of ferro-alloys containing high percentages 

 of silicon and also manganese, as a result of which 

 the manufacture of sound steel by commercial 

 processes on a large scale was rendered possible. 

 These men were MM. Euverte, Pourcel, and 

 Gautier, of the Terre Noire Works. Credit should 

 also be given to Hall in America and H^roult in 

 France, who \\;ere the pioneers of the production 

 of aluminium on a commercial scale. This element 

 is now one of the most valuable available for the 

 prevention of blowholes in steel. As an instance 

 of the successful production of sound steel castings 

 at the present day Sir Robert Hadfield gives some 

 details of the casting of hydraulic cylinders for 

 cotton baling presses. These cylinders have no 

 mechanical work done upon them, but are used 

 in the cast state. They may run up to a length 

 of 30 ft. The ram measures from 7 in. to g in. 

 I in diameter. The walls of the cylinders seldom 

 \ exceed 2J in. in thickness, and have to stand the 



NO. 2583, VOL. 103] 



hydraulic test pressure of 4 tons per sq. in. The 

 steel is cast at a temperature of about 1540° C, 

 and is poured into sand moulds which are liable 

 to give off gases. Its contraction is slightly more 

 than 0*25 in. per ft., so that the mould is not 

 less than 7 in. longer than the cylinder itself" 

 when cooled down. Below 1500° C. the steel 

 quickly loses its fluidity, and not many degrees 

 lower it is quite pasty. The fact that, in spite of 

 the difficulty of meeting these conditions, satis- 

 factory cylinders can be made indicates that the 

 art of steel casting has reached a high stage of 

 technical perfection. H. C. H. C. 



PROF. }. J. T. SCHLCESING. 



AGRICULTURAL investigators in all coun- 

 tries will learn with regret of the death of 

 Prof. Jean Jacques Thtophile Schloesing at Paris 

 on February 8. Although Prof. Schloesing had. 

 attained the advanced age of ninety-four, his 

 vigour and mental alertness were unusually good,, 

 and he had had the satisfaction of seeing his son 

 continuing in his own branch of science, doing 

 work of great importance, and making a reputa- 

 tion scarcely less distinguished than his own. 



Schloesing was born at Marseilles on July 9,. 

 1824; he entered the Polytechnic in 1841, and. 

 was appointed director of the Ecole des' Tabacs 

 in 1846. There he began an important series of 

 analytical investigations the purpose of which 

 was to improve the method of detecting and esti- 

 mating the common constituents of soils and 

 plants, such as potassium, ammonium, nitric, 

 phosphoric, and hydrochloric acids, and the com- 

 mon organic acids, such as acetic, tartaric, citric, 

 oxalic, malic, and others. The current methods 

 of dealing with natural products were sometimes 

 exceedingly laborious, and lacked even the merit 

 of accuracy ; the determinations of ammonia in 

 rain-water made with all possible care by Lawes 

 and Gilbert in 1853 had involved the distillation 

 of 2 cwt. of rain and evaporation of- the distillate 

 with sulphuric acid ; even then the- results came 

 out something like 100 per cent, too high. It is 

 impossible, therefore, to over-estimate, the Value 

 of careful analytical investigations such as those 

 made by Schloesing. 



His next imf)ortant series of investigations 

 was on the soil. By a lengthy washing process 

 he obtained a preparation of the finest clay particles 

 which remained indefinitely suspended in pure 

 water, but could be precipitated by traces of a* 

 calcium or magnesium salt. This was commonly 

 regarded as being in some sense the essential 

 clay, and agricultural chemists marvelled at the 

 minute amount present even in heavy soils. The- 

 conception served a useful purpose, but it has now 

 been replaced by a broader one : the soil is now 

 considered to be made up of particles varying' from- 

 I mm. downwards to molecular dimensions, the 

 different groups merging one into another without 

 perceptible breaks. The clay group is assigned 

 for convenience an upper limit of o''002 -iiim. , but 

 this is regarded as purely conventional.' • 



