82 REPORT — 1861. 



They were all formed for burning a mixture of coal-gas and atmospheric air, so 

 regulated as to produce great heat and no light. The construction of the burners 

 ■was explained, and the methods of securing the proper results. The same burner 

 could be made to give a single large flame for the ig-nition of a crucible, or a gi-eat 

 number of small flames proper to warm a cun-ent ot air to effect evaporations, &c. 

 Jackets or furnaces were used for applying the heat produced by the burners so as 

 to combine the greatest efl'ect with economy in the use of gas. With one of these 

 burners (the third in the series) five gallons of water could be readily boiled ; a 

 5-uich clay crucible could be raised to a fidl red heat in less than half an hour ; or 

 30 lbs. of lead or 20 lbs. of zinc coidd be kept in constant fusion. For very high 

 temperatures a blast gas furnace is required. The bmner belonging to this appa- 

 ratus contains sixteen or twenty-six blowpipes which are acted on by a bellows. 

 With this furnace, a quarter of a hmidi-edweight of cast iron, and smaller quantities 

 (two or three poimds) of such metals as malleable iron and nickel, can be com- 

 pletely fused in about an hour. 



Note on the Sulphur Compound formed by the Action of Sulphuretted Hydro- 

 gen on Formiate of Lead at a High Temperature. By W. J. Hitrst, Student 

 of Owens College, Manchester. 

 In 1856, Limpricht* assigned to the above body, aa the result of his sulphur 



determinations only, the formula ^ ^ > S^, and the name thioformic acid, from 



FT O I 



a supposed analogy to the thiacetic acid of Kekuli^tj ji ^ ^\ ^2- ^ lately im- 



dertook, at Professor Roscoe's suggestion, the following further examination of its 

 properties and mode of formation. 



(I.) When anhydi'ous formic acid is acted on by pentasulphide of phosphorus, 

 aa in Kekul^'s experiment, sulphuretted hydrogen is continually evolved, and the 

 distillate contains no sulphui' in combination. 



(II.) When the mixtm-e is heated in closed tubes to 106° C, or (III.) to the same 

 temperature under a pressure of three atmospheres, carbonic oxide and sulphuretted 

 hydrogen are evolved, with similar negative results. 



So (FV. and V.) when formiate of lead and pentasulphide of phosphorus are 

 distilled together both in the diy and moist state. These facts seem to point to a 

 decomposition of the thioformic acid, if formed, at the temperatui'e of the experi- 

 ments. Thus, 



I obtained Limpricht's body by his method, but in much smaller quantities than 

 he mentions. After purification by repeated ciystallizations from hot formic acid, 

 and drying in vacuo over sidphuric acid, analyses yielded the following results : — 

 Poxmd. Calculated for 



^ * s the formula C, HO.^ 1 e 



(I.) (II.) (III.) (IV.) 'H ]""- 



C 27-93 29-25 ^8-21 . . 19-3 



H 4-70 4-83 5-23 .. 3-2 



S 58-11 . . 56-7 55-15 51-6 



O . . . . . . . . 25-9 



Limpricht's numbers were— 



C 26-1 

 H 5-6 

 S 51-2 

 O .. 



I estimated the sulphur by oxidation with warm nitric acid, observing the neces- 

 sary precautions; the caibon and hydrogen after Carina' | method; and after the 



* Ann. Cliem. Pharm. xcvii. 3G1. 



t Ann. Chem. Pharm. xc. 309; and Phil. Mag. [4] vii. 518. 



J Aim. Pharm. cxvi. 1. 



