156 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[May, 



dose of claret or champagne, it being most palpable and notorious that 

 all our Anglo-Grecian architecture betrays utter want of invention. 

 Invention forsooth I tlien invention must' consist in making fac-similes 

 of Grecian column?, and poking plenty of sash windows between them ; 

 or in showing ugly chimneys, garret windows, and skylights over Gre- 

 cian entablatures more faithfully than tastefully copied for the nonce, or 

 if invention be occasionally shown, it is done after the fashion of Xash 

 and Smirke, the former of whom has given us a Grecian Doric order 

 in a palace, without triglyphs or even any division of frieze and archi- 

 trave in its entablature, while the other has introduced doors not at 

 all better than those of a stable or coach-house into the classical por- 

 tico of Covent Garden theatre, xaid to be copied from that of the 

 Parthenon, and whose columns some unlucky gin-and-water critic has 

 described as Ionic ! 



If S. L. can now explain away some of his own very awkward and 

 untoward remarks, all well and good. To do so would at least display 

 some ingenuity. All that I am afraid of is, that he will not make the 

 attempt, but that he will henceforth be cautious of getting into a 

 scrape by taking the part of the Professor of architecture, and leave 

 the latter either to defend himself, or to submit to the incorrigible 

 sauciness of 



Caxdidus. 



THE ROYAL EXCHANGE. 



Sir — If I am rightly informed the design for the New Royal Ex- 

 change has undergone considerable changes and modifications, espe- 

 cially as regards the interior court, in respect to which, if no other 

 part, there certainly was great room for improvement, therefore as far 

 as architectural character is concerned, I am willing to believe that 

 improvement has been made. But why is the Exchange itself to be 

 an open court at all? others besides myself have asked tlie same 

 question — at least have animadverted upon the absurdity of making 

 the area in which the merchants are to assemble an uncovered one, 

 with no other shelter from the weather than what will be afforded by 

 the ambulatories around it. The inconveniences attending such a 

 plan are obvious enough ; what countervailing advantages are expected 

 it is difficult to guess, but it may be presumed that they are suthciently 

 important ones ; consequently it would be but proper that they should 

 be stated, if only in order to exonerate those who have control over 

 the building from the charge of being guided as to so very important 

 a point solely by obstinate caprice, and adopting what will be a serious 

 inconvenience for no better reason at all than because it existed in the 

 former structure — when, by the by, it was at one time contemplated 

 to obviate it by covering in the open area. It would seem that noiv 

 it is known that the building is to be erected by Mr. Tite, all interest 

 in regard to it has entirely subsided. This ought not to be; nor ought 

 such matters to go to sleep, and be treated as if utterly indifferent, 

 because no one has now any thing farther to expect from any change 

 that may take place. If reasons or any thing like reasons can be 

 alleged for leaving the body of the Exchange entirely exposed to the 

 weather, let them be stated and then we shall know on what grounds 

 it has been determined to adhere in the new building, to what many 

 considered an inconvenience in the former one. 



There is, I find, an article on the Royal Exchange in the Penny 

 Cyclopopdia,in the course of which objection is made to the merchant's 

 area bein^ left uncovered in the new structure. What is there said, 

 however, is not likely to attract attention — at all events not immedi- 

 ately, or so mucli as a few lines in your Journal. 



I remain, &c., 



Civis. 



London, April 14, 1S41. 



MR. MUSHET'S PAPERS ON IRON AND STEEL. 



Sir — I lately had for the first time an opportunity of looking into 

 Dr. Ure's very elaborate dictionary, and on referring' to the article on 

 Iron I was a good deal surprised to find that a table of the proportions of 

 charcoal used in the fusion of bar or malleable iron to produce the 

 various qualities of steel and cast iron, and published by me in the 

 Philosophical Magazine nearly 40 years ago, had been subjected to 

 severe and unmerited censure on the part of Dr. Ure for its want of 

 accuracy.* 



As this table (along with many papers principally on the subject of 

 iron) has lately been republished at a very considerable expense, I 



■■ See Mushet's papers on iron and steel, published last year by Mr. Weale. 



consider it behoves me to protect the property so created, and to take 

 care that where the work is free from error, it shall not suffer any de- 

 terioration by my silence in respect of the criticisms of others, in what- 

 ever spirit they may be expressed. 



Tlie criticism to which I allude ("page 71G of tlie second edition of 

 Dr. Ure's Dictionary), is evidently borrowed from Karsten, but as the 

 matter does not stand in the Dictionary in inverted commas, I am en- 

 titled to assume that it contains Dr. Ure's opinion on the subject, and 

 shall deal with it accordingly. It is as follows. 



"According to Karsten, Musliet's table of the quantities of carbon 

 contained in different steels and cast irons is altogether erroneous. It 

 gives no explanation why, with ecpial portions of charcoal, cast iron at 

 one time constitutes a gray soft granular metal, and at another a white 

 hard brittle metal in lamellar facets. The incorrectness of Mushet's 

 statement becomes most manifest when we see the white lamellar cast 

 iron melted in a crucible lined with charcoal take no increase of weight, 

 while the gray cast iron becomes considerably heavier." 



In this extract two facts are alleged, namely, first, that the product 

 obtained at different times by the fusion of the same quantities of the 

 same iron with similar proportions of charcoal is irregular; and se- 

 condly, that gray cast iron acquires weight by its fusion with charcoal, 

 while white iron does not. I deny both these allegations, — but sup- 

 posing they were true, what has my table of proportions to do with 

 them ? 



It is assumed by Dr. Ure that the table gives the atomic proportions 

 of carbon united unth, and existing in, the various qualities of steel and 

 cast iron, whereas it only professes to give the proportions of charcoal 

 required to be presented to bar iron in the crucible to afford the various 

 qualities of the metal before alluded to, and this it does with a degree 

 of accuracy which I challenge Dr. Ure and Karsten to disprove. 



The experiments show in the clearest manner that charcoal is ab- 

 sorbed by iron ; that gray iron absorbs a greater quantity than white, 

 and that steel requires for its production a less proportion than white. 



To guard against the inference which has been so inconsiderately 

 drawn by Dr. Ure, the following passage was inserted in my work.* 



" Although this is the quantity of charcoal necessary to form these 

 various qualities of metal by this mode of syntheses, yet we are by no 

 means authorised to conclude that this is the proportion of real car- 

 bonaceous matter taken up by the iron, seeing that in experiments 

 Nos. 1 to G inclusive, the weight gained by the iron was upon the 

 average equal only to 1-21-jij part, whereas the charcoal which disap- 

 peared in the different fusions amounted to GIJ per cent, of the original 

 quantity introduced along with the iron." 



Having in this paragraph taken the precaution to guard against 

 misrepresentation, I am at a loss to account for the conclusions at 

 which Dr. Ure has arrived. 



It is quite evident that both he and Dr. Karsten are puzzled with 

 some results for which they have not been able to account. They can- 

 not, it would seem, explain why " cast iron (query, white, gray or 

 motled) with the same proportion of charcoal sometimes makes white 

 iron, and sometimes gray." Having had some experience in the treat- 

 ment of iron, it is barely possible that I may be able satisfactorily to 

 solve the difticulty, the weight of which they have flung upon my 

 table of proportions. 



I must in the first instance be allowed to deny the alleged fact, 

 namely, that the same iron and charcoal are so capricious as at one 

 time by their fusion to produce white cast iron, and at another time 

 gray. The same substances which have once made gray iron will, if 

 the operation be similarly conducted, do so on every occasion, and the 

 same remark holds good in respect to the other varieties of the metal. 



In order 'to understand this curious and not unimportant subject, it 

 must be laid down as a maxim that the aflinity between iron and car- 

 bon depends upon the degree of temperature which the iron will with- 

 stand before it enters into fusion: the higher the temperature short of 

 fusion, the more rapid and extensive will be the combination: and the 

 converse is equally true. 



Hence the unerring certainty with which malleable iron and steel 

 unite with carbon in the crucible, and become with an increase of 

 weight rich carburets of iron. The same remark is applicable in de- 

 gree to refined metal, which when of the purest and whitest fracture, 

 will with its appropriate dose of charcoal also pass into the state of 

 the most perfect gray iron. But the case is most materially altered 

 when the experiment is performed with common white pig-iron or 

 with gray : the greater fusibility of both these states of the metal does 

 not leave time for the action of affinity to take place between the iron 

 and charcoal, so that even with a higher proportion of charcoal the 

 results come from the crucible to all appearance unchauged as to 

 quality. 



' I'age 526, to.varils the bot om. 



