Arkansas true Democrat., 1858-03-16
Excessive Heat in Steamboat Boilers


 We reply, for various reasons. l. NIT. Evans appears to have had little of that worldly wisdom through which mar adapts himself to the prejudices and interests of his felow-men. He made, it is said, many enemies He was more successful in making useful inventions than in having them generally adopted.
 2 The large Safety Guard (the only one worthy of name) costs money-not more ln- deed than large mirrer or new carpet for the ladies cabin: but the mirror and the carpet make a show in the eyes of all the passengers, while the safety guard makes none. Ninety nine ra- veers in a hundred neither know nor care whether boat is, or IS rot supplied with safety guard of proper dimensions and proper contruc- ton.
 3. Various objections have been urged against the use of fusible alloys; all of which we may, if it be necessary, hereafter consider The chief cause of the safety guards not being introduced into general use, is preudice against it on the part of engineers. We call it prejudice be- cause it is not founded on either reason or ex- perience, but has its origin in a msconception of the nature of the action of the safety guard, and want of acquaintance with the great dan ger there is from excessive heat in a steamboat boiler no matter from what cause that excess may arise.
 great many engineers seem to suppose that, all they need care for is, that there be not too little water in the boiler as indicated by the guage cock; nor too much pressure as indicated by the steam guage They seem to forget that guage cocks do not always tell true, and that steam guages are liable to get out of oTder.- They seem not to know that boilers have been burst when well supplied with water, and when the steam guage indicated no more than an or dlnary degree of pressure Of dangers from ex- cessive heat, they appear to have little concep- tion
 Of the views of this class of engineers, we have a curious example in pamphlet by one of their number Mir. Johu +. Smith, which pamphlet was published by him at New Orleans in the year 1852, but before the steamboat law was enacted:
 In respect to Evans Safety Guard, it may be proper to state, whatever may be claimed for this invention, that they have been known to % of or blow out, ill cases N here there has been a sufficency of water in the boiler, and under less pressure of steam than may be car ried with safety with good boilers; and have therefore, in many instances been laid aside"
 Here find the very excelency of MT. Evans invention, is "going off, or " blowing out' from the action of heat alone, independ- e1tly of all other causes, made the strong ob- iecton to 1t.
 If you meet with an engineer who is duly aware of the danger there is from excessive heat in boiler, and of the importance of provid- ing prompt relief, you will. ten to one, find him ill favor of fusbe alloys as applied in Evans Safety Guard. On the othe hand, if you meet with all engineer who suPposes that too little wa ter and too much pressure are all he has to guard against you must not be surprised if you find him complaining of Evans Safety Guard, or even the alarum, as an annoyance, if not nuisance
 We beg that we may not be understood as bringing a general charge of want of intel- gence or want of ability against this class of engineers. In other respects they may be as intelligent and as able as their brethren: but they have not given to the danger that arises from too great heat in boilers, that attention which the subject from It's great importance de- serves
 It is astonishing that there should be among them such a disregard of the dangers from ex- cessive heat, when those dangers have been SO distinctly pointed out by various writers We will give by way of example, some extracts from "The Western Boatsman,' for March, 1849, periodical then published by Capt. Da- wis Embree, the present supervising inspector of the St. Louis district:
 "Af,er steam is once formed, it may be hea- ted to nearly the same intensity as the flame used in our common furnaces; this IS called sur charged or unsaturated steam. The eelastic force does not correspond with the amount If heat, as compared with common or saturated steam: the difference is set down by Professor Renwicl as 2 is to l5-onlv one tenth of the force of saturated steam.
 Uusaturated or surcharged steam at a tem- peralur" ot 333 degrees, produces pressure of lOO pounds to the square inch, while the force of saturated steam, al the same temterature. would be 9l5 pounds or more than g to l. Franhlia Institute
 Elastic steam at 335 degrees of heat. pro- duces pressure c. 12O pounds to the square inch; yet the steamer Little Rock, on Alabama (q"ery ArkaIsasO river, while carrying steam at lZUpouHds 10 the inch, and water flush at the guage cocks, when lyirg still at the shore, had the lead joints of her stelm pipe at the top of her boilers, to melt out. This required accor ding to the ables, temperature of G12 de- grees.- franhi'n Institute
 Similar cases were known to occur on the steamers Paul Jones, Tuscumbia and Wavellv. where boilers were known to burst, but the force of the steam is not known.
 < It often happens that the solder of the sleeve of the steam pipe at the engine mets, aiterthe boat has been sometime stopped, while the safety valve does not indicate any additional pressure; and after starting the engine it again chlls. The tuslng temperature of common steam pipe solder, is about 450 degrees, or. in the Instance cited, 1l3 degrees excess over that indicated by the safety valve.-A Practical Coppersn,ih.
 Mr. Perkins succeeded in heating unsatura- ted steam to temperature which would. ac- cordn2 to the theory of pressure by saturated steam, be equal to $500 pounds, but which did not exert pressure over 15O pounds Hence we find steam sometimes within boiler, of im- mense heat, with but little pressure
 Hemp burns at temperature of 457 de. grees, which would produce a pressure of 500 pounds to the inch, with saturated steam. vet how often IS the hemp packing of a cylinder burned when no such pressure is found in the boiler. *
 Some engineers speak of Juraing the steam of killing d, or destroying it's elasticity: and they can smell this burning, and when it takes place, it is time to look out for danger. This Is arriving very nearly at the truth of the mat ter without pointing out the causes.
 With the water that supplies the boilers there is always incorporated more or less atmos- pheric air. When iron is heated above 382 de- grees, Cor the repulsive poinD it imbibes the oxygen of this air, and permits the heated nitro gen with which it was incorporated to escana