V.-On the Origi78 of iiusculur Power. By E. FRANKLAND, F.R.S. [From the Philosophical Magazine for September 1866.J UNDERthis title there appeared in a recent number of the Philosophical Magazine an able article by Professom Fic k and Wislic enus," in which these gentlemen describe the results of experiments made upon themselves before during and after an ascent of the Faulhorn in Switzerland. In these experiments the amount of measured work performed in the ascent of the mountain was shown to exceed by more than three-fourths the amount which it would be theoretically pos-sible to realize from the maximum amount of muscle-oxidation indicated by the total quantity of nitrogen in the urine. The data afforded by these experiments appear to me to render utterly untenable the theory that muscular power is derived from muscle-oxidation.Nevertheless in the appli- cation of these data to the problem under consideration one important link was found to be wanting viz. the amount of actual energy generated by the oxidation of a given weight of muscle in the human body. Fick and Wislicenus refer to this missing link in the following words :-'' The question now arises what quantity of heat is generated when muscle is burnt to the products in which its constituent elements leave the human body through the lungs and kidneys? At present unfortunately there are not the experimental data required to give an accurate answer to this important question; for neither the heat of combustion of muscle nor of the nitrogenous residue of muscle (urea) is known." Owing to the want of these data the numerical resulta of the experiment of Fick and Wislicenus arerendered less toll-clusive against the hypothesis of muscle-oxidation than they otherwise would have been ; whilst similar determinations which have been made by Edward Smith Haughton Play- fair and others are even liable to a total misinterpretatioil from the same cause.I have endeavoured to supply this want by the calorimetrical determiriation of the actual energy evolved by the combustion * Phil Mag. vol. xxxi p. 485. VOL. XXI. D FRANKLAND ON THE of muscle and of urea in oxygen; but inasmuch as uric and hippuric acids frequently appear in the urine as products of a less perfect muscle-oxidation I have also determined the calorific value of these substances and have added purified albumin and beef fat to the list.Creatine would also have been included; but although I was furnished with an ample supply of this substance through the kindness of Mr. Dittmar all attempts to burn it in the calorimeter were fruitless. In nume-rous trials under varied conditions it always exploded violently on ignition. The determination of the actual energy developed by the combustion of the above-named substances is surrounded by formidable difficulties which have probably prevented its pre-vious execution. It is impossible to effect the complete com- bustion of these bodies in oxygen gas under conditions which permit of the accurate measurement of the heat evolved; but preliminary experiments showed that complete oxidation could be secured by deflagration with potassic chlorate ; and although this method is doubtless inferior in accuracy to the calori- metrical methods usually employed it is hoped that with the corrections described below the results obtained merit sufficient confidence to render them useful in subsequent discussions of' this and allied subjects.The determinations were made in a calorimeter devised some years ago by Lewis Thompson and which I have repeatedly used with satisfaction in other estimations of a like kind. This instrument consists of a copper tube which is made to contain a mixture of potassic chlorate with the combustible substance and can be enclosed in a kind of dhing-bell also of copper and so lowered to the bottom of a suitable vessel containing a known quantity (two litres) of' water.The experiments were conducted in the following manner :-19-5 grams* of potassic chlorate to which about one-eighth of manganic oxide was added were intimately mixed with a known weight (generally about two grms.) of the substance whose thermal value was to be determined; and the mixture being then placed in the copper tube above mentioned a small piece of cotton thread previously steeped in a solution of potassic chlorate and dried was inserted in the mixture. The temperature of the water in the calorimeter was now carefully * I follow the example of the Registrar-General in abbreviating the French word grarnme to gram.ORIQIN OF MUSCULAR POWER. ascertained by a delicate thermometer and the end of the cotton thread being ignited the tube with its contents was placed in the copper bell and lowered to the bottom of the water. As Boon as the combustion reached the mixture a stream of gases issued fiom numerous small openings at the lower edge of the bell ajnd rose to the surface of'the water-a height of about 10 inches. At the termination of the deflagra- tion the water was allowed fkee access to the interior of the bell by opening a stopcock connected with the bell by a small tube rising above the surface of the water in the calorimeter. The gases in the interior of the bell were thus displaced by the incumbent column of water ; and by moving the bell up and down repeatedly a perfect equilibrium of temperature through- out the entire mass of water was quickly established.The temperature of the water was again carefully observed; and the difference between this and the previous observation gives the calorific power or the potential energy of the substance consumed expressed as heat. The value thus obtained however is obviously subject to the following corrections :-1. The amount of heat absorbed by the calorimeter and appa- ratus employed to he added. 2. The amount of heat carried away by the escaping gases after issuing from the water to be added. 3. The amount of heat due to the decomposition of the potas- sic chlorate employed to be deducted. 4. The amount of heat equivalent to the workperfomed by the gases generated in overcoming the pressure of the atmo- sphere to be added.Although the errors due to these causes to gome extent neu-tralize each other there is still an outstanding balance of suffi-cient importance to require that the necessary corrections should be carefully attended to. The amount of error fiom the first cause was once for all experimentally determined and was added to the increase of temperature observed in each experiment. The amount of heat carried away by the escaping gases after issuing from the water may be divided into two items viz. :-a. The amount of heat rendered latent by the water which is carried off by the gases in the form of vspour. P. The amount of heat carried off by these gases by reason of FRAXKLAND ON THE their temperature being above that of the water from which they issue.It was ascertained that a stream of dry air passed through the water of the calorimeter at about the same rate and for the same period of time as the gaseous products of combustion depressed the temperature of the water by only 0°*02C. By placing a delicate thermometer in the escaping gases and another in the water no appreciable difference of temperature could be observed. Both these corrections may therefore be safely neglected. The two remaining corrections can be best considered together since a single careful determination eliminates both. When a combustible substance is burnt in gaseous oxygen the con-ditions are essentially different from those which obtain when the same substance is consumed at the expense of the com- bined or solid oxygen of potassic chlorate.In the first cage the products of combustion when cooled to the temperature of the water in the calorimeter occupy less space than the sub- stances concerned in the combustion and therefore no part of the energy developed is expended in external work-that is in overcoming the pressure of the atmosphere. In the second case both the combustible and the supporter of combustion are in the solid condition whilst a considerable proportion of the pro- ducts of combustion are gases. The generation of the latter cannot take place without the performance of external work ;for every cubic inch produced must obviously in overcoming atmo- spheric pressure perform an amount of work equivalent in round numbers to the lifting of a weight of 151bs.to the height of 1 inch. In performing this work the gases are cooled and conaequently less heat is communicated to the water of the calorimeter. Neverthelesa the loss of heat due to this cause is but small. Under the actual conditions of the experiments detailed below its amount would only have increased the tem- perature of the water in the calorimeter by 0'97 C. Even this slight error is entirely eliminated by the final correction which we have now to consider. It is well known that the decompositiou of potassic chlorate into potassic chloride and fi-ee oxygen is attended with the evo- lution of heat; if a few grains of manganic oxide or better of feiric oxide be dropped into an ounce or two of fused potasgic chlorate which is slowly disengaging oxygen the evolution of ORIGIN OF MUSCULAR POWER.37 gas immediately proceeds with great violence and the mixture becomes visibly red-bot although the external application of heat be discontinued from the moment when the metallic oxide is added. The latter remains unaltered at the close of the operation. It is thus obvious that potassic chlorate on being decomposed furnishes considerably more heat than that which i8 necessary to gasify the oxygen which it evolves. It was therefore necessary to determine the amount of heat thus evolved by the quantity of potassic chlorate (9.75 grms.) mixed with one gram of the substarice burnt in each of the following deteI- minationbr.This was effected by the use of two copper tubes the one placedwithin the other. The interior tube was charged with a known weight of' the same mixture of potassic chlorate and manganic oxide as that used for the subsequent experi- ments whilst the annular space between the two tubes was filled with a combustible mixture of chlorate and spermaceti the calorific value of which had been previously ascertained. The latter mixture was ignited in the calorimeter as before ;and thb heat generated during its combustion effected the completc decomposition of the chlorate in the interior cylinder as was proved by a subsequent examination of the liquid in the ca,lori- meter which contained no traces of undecomposed chlorate.The following are the results of five experiments thus made expressed in units of heat the unit being equal to 1 gram of water raised through 1"C. of temperature First experiment .......... 340 Second experiment. ......... 300 Third experiment .......... 375 Fourth experiment. ......... 438 Fifth experiment .......... 438 -1891 Mean ................ 378 This result was confirmed by the following experiments :-(1) Starch was burnt first in a current of oxygen gas and secondly by admixture with potassic chlorate and manganic oxide. Heat-units furnished by 1 gym. of starch burnt with) 4290 9-75 grms. of potassic chlorate ................ Heat-units finmished by the same weight of starch } 3964 burnt in a stream of oxygen gas ............._c_ Difference .......................... 326 FRANKLAND ON THE (2) Phenplic alcohol was burnt with potassic chlorate and the reault compared with the calorific value of this substance as determined by Favre and Silbermann. Heat-units furnished hy 1 grru. of phenylic alcohol) 8183 burnt with 9975 grms. potassic chlorate.. ........ Heat-units furnished by- 1 grm. of phenylic alcohol when burnt with gaseous oxygen (Favre and Sil- 17842 be r m a nn) .................................. -Difference .......................... 341 These three determinations of the heat evolved by the de- composition of 9-75 grms. of potassic chlorate furnishing the numbers 378 326 and 341 agree as closely as could be ex- pected when it is considered that all experimental errors are necessarily thrown upon the calorific value of the potassic chlorate.The mean of the above five experimental numbers was in all cases deducted fi-om the actual numbers read off in the follow- ing determinations. It was ascertained by numerous trials that all the potassic chlorate was decomposed in the deflagrations and that but mere traces of carbonic oxide were produced. J o ul e's mechanical equivalent of heat was employed viz. 1 kilog. of water raised 1"C. = 423 metrekilogs. The followhg results were obtained :-Actual Energy developed by 1 grm. of each substance when burnt in Oxygen. Heat-units. Metre-1 Name of substance (dried at 100"(2.).1st 2nd 3rd Exp. Exp. Exp. Beef muscle purifiedby repeated washingwith ether ........ 5174 6062 6195 5088 5103 2161 Purified albumin .... 6009 4987 .. .. 4998 2117 Beef fat ............ 9069 .. *. 9069 3841 Hippuric acid.. ...... Uric acid.. .......... 5330 2645 5k& 2585 .. *. 5383 2615 2280 1108 Urea .............. 2131 2302 2207 2i97 2206 934 It is evident that the above determination of the actual ORIGIN OF MUSCULAR POWER. energy developed by the combmtion of muscle in oxygen re- presents more than the amount of actual energy produced by its oxidation within the body because when muscle burns in oxygen its carbon is converted into carbonic anh-ydride and its hydrogen into water? the nitrogen being to a great extent evolved in the elementary state ; whereas when muscle is most completely consumed in the body the products are carbonic anhydride water and urea the whole of the nitrogen passeg out of the body as urea a substance which still retains a con- siderable amount of potential energy.Dry muscle and pure albumin yield under these circumstances almost exactly one- third of their weight of urea ; and this fact together with the above determination of the actual energy developed in the combustion of urea enables us to deduce with certainty the amount of actual energy developed by muscle and albumin respectively when consumed in the human body. It is as follows :-Actual Energy developed by 1 grm. of each substance when con-sumed in t7te body.Name of substance (dried at Heat-units 1 Metreki'oge' of force 1 100"0.). (Mean)* (Mean). Beef muscle purified by ether . . 1848 Purified albumin . . . . . . . . . ,. 1 "4: 1 1803 Interpolating the data thus obtained into the results of Fick and Wislicenus's experiments let us now compare the amount of measured and calculated work performed by each of the ex-perimenters during the ascent of the Faulhorn with the actual energy capable of being developed by the maximum amount of muscle that could have been consumed in their bodies this amount being represented by the total quantity of nitrogen excreted in each case during the ascent and for six hours after- wards. FRANKLAND ON TTJE Pep------Actual energy capable of being pro- ] I duced by the consumption of 68,690 68,376 37.17 and 37-00 grms.of dry metrekilogs. metrekilogs. muscle in the body . . . . . . . . . Measured work performed in the 129,096 148,656 ascent (external work) . . . . . . . . } metrekilogs. metrekilogs. Calculated circulatory and respira- 35,631 tory work performed duringthe ascent (internal work) . . . . . . . . metr&ilogs. metrekilogs. 159,637 184,287 Total ascertainable work performed. . metrekilogs. metrekilogs. I { 1 The actual energy capable of being produced by the com-sumption of 37.17 and 37.00 grms. of dry muscle in the body was estimated by Fick and Wislicenus at 106,250 and 105,825 metrekilogs. The experimental determination of the actual energy deve- loped by the muscle-oxidation renders it now abundantly evident that the muscular power expended by these gentlemen in the ascent of the Faulhorn could not be exclusively derived from the oxidation either of their muscles or of other nitro- genous constituents of their bodies since the maximum of power capable of being derived from this source even under very fdvourable assumptions is in both cases less than one-half of the work actually performed; but the deficiency becomes much greater if as Fick and Wislicenus have done we take into coiisideration the fact that the actual energy developed by oxidation or combustion cannot be wholly transformed inbo mechanical work.In the best-constructed steam engine for instance only one-tenth of the actual energy developed by the biirning fuel can be obtnined in the form of mechanical power; and in the case of man Helmholtz estimates that not more than one-fifth of the actual energy developed in the body can be made to appear as external work.The experiments of Heidenhain however show that under favourable circum- stances a muscle may be made to yield in the shape of mechanical work as much as one-half of the a~timlenergy developed within it the remainder assuming the form of heat. ORIGIN OF MUSCULAR POWER. Taking then this highest estimate of the proportion of mechanical work capable of being got out of actual energy it becomes necessary to multiply by 2 the above numbers repre- senting the ascertainable work performed in order to express the actual energy involved in the production of that work.We then get the following comparison of the actual energy capable of being developed by the amount of muscle consumed with the actual energy necessary for the performance of the work executed in the ascent of the Faulhorn. Fick. Wislicenus. me trekilogs. metrekilogs. Actual energy capable of being pro. 68,376 68j690 duced by muscle-metnmorphosis } Actual euergy expended in work} 319,274 performed . . . . . . . . . . . . . . . . . 368,574 Thus taking the average of the two experiments it is evident that scarcely one-fifth of the actual energy required for the work performed could be obtaJned from the amount of muscle consumed. Interpreted in the same way previous experiments of a like kind prove the same thing though not quite so conclusively.To illustrate this I will here give a summary of three sets of ex-periments,-the first made by Dr. E. Smith upon prisoners en- gaged in treadmill labour ; t8he second by the Rev. I>. Haugh-to 11 upon military prisoners engaged in shot drill ; and the third adduced by P1a y fa i r and made upon pedestrians pile-drivers men turning a winch and other labourers. =I;*eadJwheel Bxperiments. A treadwheel is a revolving drum with steps placed at dis- tances of 8 inches and the prisoners are required to turn the wheel downwards by stepping upwards. Four prisoners designated below as A B C and D were employed in these experiments ; and each worked upon the wheel in alternate quarters of an hour resting in a sitting posture during the in- tervening quarters.The period of actual daily labour was 3+ hours. The total ascent per hour 2,160 feet or per day 1.432 mile. The following are the results :- FRANKLAND ON THE Treadwheel Work. (E. Smith.) Weight of oczgd Ascent in work per-metres. formed in 1 zt:&T corresponding in ascent* metrekilogs. 1 to nitrogen. grms. grms. A 47.6 23,045 10 1,096,942 171.3 1101 *2 B 49 23,045 10 1,129,206 174 -6 1121'7 C 65 20,741 9 1,140,755 168 *O 1080 *1 D 56 20,741 0 1,161,496 159 -3 1024 *3 I In these experiments the measured work was performed in the short space of three and a-half hours whilst the nitrogen estimated was that voided in the shape of urea in 24 hours. It will therefore be necessary to add to the measured work that calculated for respiration and circulation for the whole period of' 24 hours.This amount of internal work was computed from the estimates of Helmholtz and Fick as follows :-Internal Work. (Hel rnh o 1t z and Fic k.) I Work Actual energy I performed. required. -I__---j metrekilogs.+ me trekilogs. Circulation of the blood during 24 138,240 hours at 75 pulsations per minute} 69,120 Respiration for 24 hours at 12 pul-10,886 sations per minute ........... 21,772 I Statical activity of muscles Not determfped Not determined. Peristaltic motion ........ I , -7 ? ! 80,006 160,012 Taking this estimate for internal work the average results of the treadwheel experiments may be thua expressed :-Treadwheel 'c.tlbrk.Average external work per nian per } 119,605 metrekilogs. day ............................ Average nitrogen evolved per man} per day ........................ 17.7 grms. *t Since making use of this number I find that Dondera estimates the work of the heart alone for twentyfour hours at 86,000 metrekilograms 8 figure which is higher than thadt used above for the combined work of circulation and reapirstion. ORIGIN OF MUSCULAR POWER. IZreadwheeZ W orL-(Continued. j Weight of dry muscle corresponding } 114grms. to average nitrogen evolved per day Actual energy producible by the con- sumption of 114 grms. dry muscle 210,672 metrekilogs. inthebody .................... Average actual energy developed in the body of each ninn v1z.:-External work.. ...... 119,605 x 2 = 239,210 metrekilogs. Circulation .......... 69,120 x 2 = 138,240 9 Respiration .......... 10,886 x 2 = 21,772 97 399,222 79 In these experiments the conditions were obviously very un- favourable for the comparison of the amount of actual energy producible from muscle-metamorphosis with the quantity of actual energy expended in the performance of estimable work since during that portion of the 24 hours not occupied in the actual experiment a large amount of unestimable internal work such as the statical activity of the muscles peristaltic motion &c. was being performed. Nevertheless these experiments show that the average actual energy developed in producing work in the body of each man was nearly twice as great as that which could possibly be produced by the whole of the nitro- genous matter oxidized in the body during 24 hours.It must also be remarked that the prisoners were fed upon a nitro- genous diet containing six ounces of cooked meat without bone -a diet which as is well known would favour the production of urea. Shot-drill Experiments. The men employed for these experiments were fed exclusively upon a vegetable diet and they consequently secreted a con- siderablx smaller amount of nitrogen than the flesh-eaters engaged in the treadwheel work ; the other conditions were FRANKLAND ON THE however equally unfavourable for showing the excess of work performed ' over the amount derivable from muscle-metamor-phosis.In shot drill each man lifts a 32-lb. Rhot fi-om a tressel to his breast a height of 3 feet ;he then carries it a distance of 9 feet and lays it down on a similar support returning unloaded. Six of these double journeys occupy one minute. The men were daily engaged wit,h Shot drill.. ................ 3 hours. Ordinary drill. ............. 14 7 Oakum-picking ............ 3+ , The ,total average daily external work was estimated by Haughton at 96,316 metrekilogs. per man. The followjng is a condensed summary of the results of these experiments :-Military Vegetarian Prisoners at Shot Drill. (H au gh t on.) Average external work per man per} 96,316 metrekilogs. day ............................ Average nitrogen evolved per man) 12.1 grms.per day ........................ Weight of dry muscle corresponding) 71,9 9, to average nitrogen evolved per day Actual energy producible by the con- sumption of 77.9 grms. of dry muscle 143,950 metrekilogs. in the body .................... Average actual energy developed daily in the body of each man viz. :-External work 96,316 x 2 ........ = 192,632 metrekilogs. Internal work.. .................. = 160,012 91 352,644 7 Owing chiefly to the vegetable diet of these prisoners thiR result is more conclusive than that obtained upon the tread- wheel the amount of work actually performed being conside- rably more than twice as great as that which could possibly be obtained through the muscle-metamorphosis occurring in t,he bodies of the prisoners.ORIGIN OF MUSCULAR POWER. Playfair’s Determinations. In these determinations the number 109,496 metrekilograms was obtained as the average amount of daily work performed by pedestrians pile-drkers porters paviors &c.; but as the amount of muscle consumption is calculated from the nitrogen taken in the food the conditions are as unfavourable as possible with regard to the point I am seeking to establish; for it is here assumed not only that all the nitrogen taken in the food enters the blood but also that it is converted into muscle and is after- wards oxidized to carbonic anhydride wat.er and urea. The following are the results expressed as in the previous cases :-Hurd-worked Lnbourer (Play fair).1 I Work Actual energy performed. required. mtrekilogs. metrekilogs. Daily labour (external work) . . 109,496 21 8,992 80,006 160,012 Internal wark.. .. .. .. .. .. . . . ---189,502 379,004 Actual energy capable of being produeed from 5.5 02. (155.92 grms.) of metrekile. flesh-formers contained in the daily food of the labourer.. . . . . . 288,140 Thus even under the extremely unfavourable conditions of these determinations the actual work performed exceeded that which could possibly be produced through the oxidation of the nitrogenous constituents of the daily food by more than 30 per cent. We have seen therefore in the above four sets of experi-ments interpreted by the data afforded by the combustion of muscle and urea in oxygen that the transformation of tissue alone cannot account for more than a small fraction of the mus- cular power developed by animals ; in fact this transformation goes on at a rate almost entirely independent of the amount of muscular power developed.If the mechanical work of an animal be doubled or trebled there is no corresponding increase of nitrogen in the secretions; whilst it was proved on the other hand by Lawes and Gilbert as early as the year 1854 VOL. XXI. E FRANKLAND ON THE that animals under the same conditions as regarded exercise had the amount of nitrogen in their secretions increased two- fold by merely doubling the amount of nitrogen in their food. Whence then comes the muscular power of animals ? What are the substances which by their oxidation in the body furnish the actual energy whereof a part is converted into muscular work? In the light of the experimental results detailed above can it be doubted that a large proportion of the muscular power developed in the bodies of animals has its origin in the oxidation of non-nitrogenous substances ? For whilst the secretion of nitrogen remains nearly stationary under widely different degrees of muscular exertion the production of carbonic anhydride in- creases most markedly with every augmentation of muscular work as is shown by the following tabulated results of E.Smith's highly important espepiments upon himself re-garding the amount of carbonic anhydride evolved under dif- ferent circumstances." Excretion of carbonic anliydride during rest and mnscalar exertion :-Carbonic anhydride per hour.During sleep ...................... 19.0 grams. Lying down and sleep approaching .. 23.0 , In a sitting posture ................ 29.0 , Walking at the rate of 2 miles perhour 70.5 , Walking at the rate of 8 miles per hour 100.6 , On the treadTvhee1 ascending at the rate of 28.65 feet per minute ...... 189.6 , Jt is admitted on all hands that food and food alone is the ultimate source from which muscular power is derived; but the above determinations and considerations prove conclusively first that the non-nitrogenous constituents of the food such as starch fat &c. are the chief sources of the actual energy which becomes partially transformed into muscular work; and secondly that the food does not require to become organized tissue before its metamorphosis can be rendered available for muscular power its digestion and assimilation into the circulating fluid (the blood) being all that is necessary for this purpose.It is how- ever by no means the non-nitrogenous portions of food alone JI Phil. Trans. for 1859,p. 709. ORIGIN OF MUSCULAR POWER. that are capable of being so employed-the nitrogenous also inasmuch as they are combustible and consequently capable of furnishing actual energy might be expected to be available for the same purpose; and such an expectation is confirmed by the experiments of Savory upon rats,* which show that these animals can live for weeks in good health upon food consisting almost exclusively of muscular fibre.Even supposing these rats to have performed no external work nearly the whole of their internal muscular work must have had its source in the actual energy developed by the oxidation of their strictly nitro- genous food. It can scarcely be doubted however that the chief use of the nitrogenous constituents of food is for the renewal of mus- cular tissue-the latter like every other part of the body requiring a continuous change of substance ; whilst the chief function of the non-nitrogenous is to furnish by their oxidation the actual energy which is in part transmuted into muscular force. The combustible fQod and oxygen coexist in the blood which courses through the muscle; but when the muscle is at rest there is no chemical action between them.A command is sent from the brain to the muscle the nervous agent determines oxidation. The potential energy becomes actual energy one portion assuming the form of motion another appearing as heat. Here is the source of animal heat here the origin of muscular power! Like the piston and cylinder of a steam-engine the muscle itself is only a machine for the transformation of heat into motion; both are subject to wear and tear and require renewal ; but neither contributes in any important degree by its own oxidation to the actual production of the mechanical power which it exerts. From this point of view it is interesting to examine the various articles of food in common use as to their capabilities for the production of muscular power.I have therefore made careful estimations of the calorific value of different materials used as food with the same apparatus and in the same manner as described above for the determination of the actual energy in muscle urea &c. The results are embodied in the following series of tables; but it must be borne in mind that it is only on the condition of the food being digested and passed into the * The 1 ancet 1863,pages 381 and 412. E2 FRANKLAND ON THE blood. that the results given in these tables are realized . If. for instance. sawdust or paraffin oil had been experimented upon. numbers would have been obtained for these substances. the one about equal to that assigned to starch.and the other surpasaing that of any article in the tables ; but these numbers would obviously have been utterly fallacious. inasmuch as neither sawdust nor paraffin oil is. to any appreciable extent. digested in the alimentary canal. Whilst the force-values experimentally obtained for the different articles in these tables must. therefore. be understood as the maxima assignable to the substances to which they belong. yet it must not be forgotten that a large majority of these substances appear to be com-pletely digestible under normal circumstances . TABLEI.-Results of Experiments witlt Food dried at 100" C. in heat -units . Heat-Heat-Heat-Heat-Name of Food. units. units. units. units. 1st Exp. 2nd Exp 3rd Exp (Mean.) Cheshire cheese....................... 6080 6149 .. 6114 Potatoes ............................. 3752 .. .. 3752 Apples................................ 3776 3562 .. 3663 Mackerel.............................. 5994 6134 6064 Oatmeal (not dried) .................... 4143 4018 3857 4004 Lean beef ............................ 5271 5260 5410 5313 White of egg .......................... 4823 4940 492'7 4896 Carrots .............................. 3776 3759 .. 3767 Pea-meal (not dried) .................... 3866 4006 .. 3936 Flour (not dried) ...................... 3941 3931 .. 3936 Arrowroot (not dried) .................. 3923 3902 .. 3912 Butter ................................ 7237 7291 .. 7264 Ham boiled and lean ..................4188 4498 4343 Lean veal ............................ 4459 4595 4i88 4514 Hard-boiled egg ........................ 6455 61 87 .. 6321 Yelk of egg .......................... 6460 .. .. 6460 Isinglass .............................. 4520 4520 .. 4520 Cabbage .............................. 3809 3744 .. 3776 Whiting .............................. 4520 4520 .. 4520 Ground rice (not dried) .................. 3802 3824 .. 3813 Cod-liver oil .......................... 9134 9080 .. 9107 Cocoa nibs (not dried) .................. 6809 ' 6937 .. 6873 Residue of milk ........................ 5066 5120 .. 5093 Bread crumb .......................... 3984 3984 .. 3984 a. Bread crust (not dried). ................. 4459 .. 4459 Lump sugar (not dried) ..................3403 3294 .. 3348 Commercial grape-sugar (not dried) ...... 3277 8277 .. 3277 Residue from botlled ale ................ 3776 3744 .. 3'7'60 Residue from bottled stout .............. 6348 6455 .. 6401 ORlGIN OF MUSCULAR POWER. TABLE11.-Actual Energy developed by 1 gram of various Articles of Food when burnt in Oxygen. \ 1 I I Heat-units. Metrekilograms of force. Percent. Name of Food. of water. Natural Natural Dry* condition. Dry’ condition. -I_ ----.--Cheese (Cheshire) .......... 6114 4647 2689 1969 24 -0 Potatoes .................. 3752 1018 1589 429 73 -0 Apples. ................... 3669 660 1554 280 82 ‘0 Oatmeal .................. .. 4004 .. 1696 Flour ...................... 3936 .. 1669 Pea-meal................. .. 3936 .. 1667 Ground rice .............. .. 3813 .. 1615 Arrowroot ................ 3912 1657 1 Bread crumb .............. 3984 2231 1687 945 44.0 Bread crust.. .............. .. 4459 1888 Beef (lean) ................ 5313 1567 2250 664 70 -5 Veal.. .................... 4514 1314 1912 556 70 -9 Ham (boiled) .............. 4343 1980 1839 839 54 -4 Mackerel. ................ 6064 1789 2568 758 70 -5 Whiting .................. 4520 904 1914 383 80 -0 284 86 *3 White of egg .............. 4896 671 2074 Hard-boiled egg.. .......... 6321 2383 2677 1009 62 -3 Yelk of egg .............. 6460 3423 2737 1449 47 *o Isinglass .................. 4520 1914 Milk ....................5093 b‘s2 2157 280 87 -0 Carrots .................. 3767 527 1595 223 86 -0 Cabbage .................. 3776 434 1599 284 88 *5 Cocoa nibs ............... .. 6873 .. 2911 Beef fat .................. 9069 3841 Butter .................... .. 7ii4 .. 3077 Cod-liver oil .............. *. 9107 .. 3857 Lump sugar .............. .. 3348 .. 1418 Commercial grape-sugar .... 3277 .. 1388 Bass’s ale (alcohol reckoned). . 3i60 775 1599 328 88 -4 Guineas’s stout , .. 6401 10?6 2688 455 a8 -4 TABLE 111.-Actual Energy developed by 1 gram of various Articles of Food when oxidized in the Body. Metrekilograms of force. Name of Food. Nat,uraI Dry. condition. 1 ChePhire cheese ............ 2429 1846 Potatoes .................. Apples.................... Oatmeal .................. 1665 FRANKLAND ON THE TABLE1II.c ontinued. Metrekilograms of force. Name of Food. Natural Dry. condition. ......... Flour .........,.......... Pea-meal......,.. ........ Ground rice ,............. Arrow-root ....... ........ Bread crumb .............. Lean of beef ,............. Lean of veal ............ Lean of ham (boiled) .....,.. Mackerel.................. Whiting ....,...,......... White of egg .............. Hard-boiled egg ............ Yelk of egg ...,.......... Gelatin .................. Milk...................... Carrota ................. Cabbage .................. Cocoa-nibs ............... Butter ....................Beef fat ,............,.... Cod-liver oil .,............ Lu’mp sugar ....... ...... Commercial grape-sugar .... Bass’s ale (bottled) .......... Guineas‘s stout , .......... .. 1627 .. 1598 .. 1591 .. 1657 1626 910 2047 604 1704 496‘ 1559 711 2315 683 1675 335 1781 244 2562 966 284 1 1400 1550 2046 266 18’74 220 1543 178 .. 2902 .. 30’77 3841 3857 .. 1418 .. 1388 1559 328 2888 455 ~-TABLE 1V.-Weight and Cost of various Articles of Food required to be oxidized in the body in order to paise 140 Ibs.to the JteigJLt of 10,000 feet. External Work = one-fifth of Actual Energy. Name of Food. Weight in lbs. Price required. per lb . cost. ~ Cheshire chee8e ............Potatoes .................. Apples .................... Oatmeal .................. Flour ................... Pea-meal .................. Ground rice .............. Arrowroot ................ Bread .................... 1.156 5 -068 7-815 1.281 1-311 1 *335 1-341 1.23’7 2 -345 .. s. d. 0113 054 0 ll$ 03+ 039 048 054 134 0 4% ORIGIN OF MUSCULAR POWER . TABLEIV-continued . Name of Food. ' 1 ~~ I Lean beef ................ Lean veal ................ Lean ham (boiled) .......... Mackerel ................... Whiting .................. White of egg .............. Hard-boiled egg............ ~ Isinglws ..................~ Milk ...................... Carrots ................... Cabbage ................... Cocoa nibs ................ Butter .................... j Beef fat ..................i Cod-liver oil ............... Lump sugar ..............\ Commercial grape-sugar .. .I Basu's pale ale (bottled) " Cfuiness's stout . ,. .. I ....I lbs required . ~~ 3 *532 4.300 3.001 3.124 6 *369 8 *i45 2 209 1 -3i7 8-021 9-685 12.020 0 -735 0.693 0 *555 0.553 1 -505 1-537 9 bottles. 6 >> Price per lb . cost. .-. a. d. 8. d. 10 3 6i 10 4 3h 16 46 08 21 14 94 06 4 4a 0 64 1 28 16 0 22 0,L 5d.per qrt . 1 33 0 14 1 2h 01 1 0% 1 6 1 1% 1' 6 1 og 0 10 0 5; 36 1 11a 06 13 0 3h 0 5f 0 10 76 0 10 5 7h Food required to sustain TABLEV.-)lespiration and Circulation in the Body oj' an average iMan Weight of various Articles of during twenty-four hours .Name of Food. Cheshire cheese ............ Potatoea .................. Apples.................... Oatmeal .................. Flour .................... Pea-myal .................. Ground rice .............. Arrowroot ................ Bread .................... Lean beef ................ Lean veal ................ Lean ham (boiled) .......... Mackerel .................. Weight in oza. 3.0 13 .4 20 *i 3 '4 3.5 3.5 3 .6 3 *4 6-4 9 *3 11 -4 7.9 8 -3 Name of Food.Weight in ozs. Whiting ................ 16-8 White of egg ............ 23.1 Hard-boiled egg .......... 5'8 Gelatin .................. 3.6 Milk .................... 21-2 Carrots .................. 25-6 Cabbage ................ 31-8 Cocoa nibs................ 1*9 Butter .................. 1-8 Cod-liver oil .............. 1.5 Lump sugar .............. 3.6 Cammercial grape-sugar .... 40 These results are fully borne out by experience in many in-stances. The food of the agricultural labourers inLancashire contains a large proporiion of fat . Besides the very fat bacon which constitutes their animal food proper. they consume large FRANKLAND ON THE ORIGIN OF MUSCULAR POWER.quantities of so-called apple dumplings the chief portion of which consists of paste in which dripping and suet are large ingredients ; in fact these dumplings frequently cdntain no fixit at all. Egg and bacon pies and potatoe pies are alsovery common pikces de rdsistance during harvest time and whenever very hard work is required from the men. I well remember being profoundly impressed with the dinners of the navigators employed in the construction of the Lancaster and Preston Railway ; they consisted of thick slices of bread surmounted with massive blocks of bacon in which mere streaks of lean were visible. These labourers doubtless find that from fat bacon they obtain at the minimum cost the actual energy required for their arduous work.The above tables affirm the same thing. They show that -55 lb. fat will perform the work of 1.15lb. cheese 5 lbs. potatoes 1.3 lb. of flour or pea-meal or of 33 lbs. of lean beef. Donders in his admirable pamphlet ‘‘ On the Constituents of Food and their relation to Muscular Work and Animal Heat,” mentions the observations of Dr. M. C. Verloren on the food of insects. The latter remarks “many insects use during a period in which very little muscular work is performed food containing chiefly albuminous matter; on the contrary at a time when the muscular work is very con- aiderable they live exclusively or almost exclusively on food free from nitrogen.” He also mentions bees and butterflies as instances of insects performing enormous muscular work and subsisting upon a diet containing but the merelst traces of nitrogen.The following conclusions may therefore be drawn from the foregoing experiments and considerations :-1. A muscle is a machine for the conversion of potential energy into mecliaiiical force. 2. The mechanical force of the muscles is derived chiefly from the oxidation of matters contained in the blood and only in a very subordinate degree from the oxidation of the muscles themselves. 3. In man the chief materials used for the production of muscular power are non-nitrogenous ; but nitrogenous matters can also be emplcyed for the same purpose and hence the greatly increased evolution of nitrogen under the influence of a flesh diet even with no increase of muscular exertion.4. Like every other part of the body the muscles are co~l- stantly being renewed ; but this renewal is scarcely perceptibly PERKIN ON THE ARTIFICIAL PRODUCTION OF COUMARIN. 53 more rapid during great muscular activity than during compa- rative quiescence. 5. After the supply of sufficient albuminoid matters in the food of man to provide for the necessary renewal of the tissues the best materials for the production both of internal and ex-ternal work are non-nitrogenous matters such as oil fat sugar starch gum &c. 6. The non-nitrogenous matters of food which find tbeir way into the blood yield up all their potential energy as actual energy; the nitrogenous matters on the other hand leave the body with a portion (at least one-seventh) of their potential energy unexpended.7. The transformation of potential energy into muscular power is necessarily accompanied by the production of' heat within the body even when the muscular power is exerted externally. This is doubtless the chief and probably the only source of animal heat.