1823.] 



On the Discoverer of Steam Engines, 



487 



for giving ships solid bottoms as high 

 as the water's edge, from the consiile- 

 ration that, 5a the Royal Navy alone, 

 upwards of 300 ships of war were lost 

 between the years 1793 and 1814, by 

 foundering and sliipwreck. 



Malcolm Cowan 

 Kirkwall; May 12, 1823. 



To the Editor of the Monthly Magazine. 



SIR, 



ALLOW me to make a few obser- 

 vations on Mr. Bartlett's remarks 

 on the nutritious effects of the farina 

 of potatoes, which he observes can be 

 obtained in the proportion of twenty- 

 eight parts to a hundred ; and that tlie 

 farina of potato is equal to arum, &c. 

 and he recommends it to be planted 

 on the Peninsula. 



In Spain they have been tried, and 

 do not succeed : they are called by tiie 

 natives a name which in Englis'i is 

 denominated toad-gut, on account of 

 their indigestible quality ; and they 

 never arrive to any size bigger than a 

 walnut, in consequence of the dryness 

 ^f their summer. Concerning the 

 farina, it varies in the different sorts of 

 potatoes, and the time of year when 

 made ; as the spring advances, and the 

 germination increases, the less farina 

 is produced : a potato that would 

 produce a fourth part of farina in 

 or about October, would hardly pro- 

 duce any at tliis time. The farina or 

 starch has a peculiar property, I be- 

 lieve, not hitherto noticed: let any 

 person take a tea-spoonful of farina 

 or potato starch, and the like qiiandty 

 of wheatcn starch; put them in diffe- 

 rent tea-cups, and fill them up with 

 boiling water, and stirring them during 

 the time: they will soon perceive that 

 made of wheat starch become opaque, 

 and the potato-starch transparent, like 

 clear jelly from isinglass ; which, I 

 think, proceeds from an acid, inti- 

 mately combined with potato-starch, 

 and whicii no cold water will dis- 

 engage. Whether tiiis acid has any 

 del{;terious property, I know not; but 

 it is probable that it is the cause of 

 the potato not drying in any process 

 to keep them. If the jelly is kojit 

 about a week cxi)oscd to the air, a 

 decomposition takes place, and it be- 

 comes opaque, and subsides, leaving 

 the water ( Icar above. 



If, through your valuable pages, any 

 correspondent will inform me what 

 acid it is that causes the difference, I 

 shall feel nnich obliged. 



J. M. 



To the Editor of the MoiUhly Magazine. 



8IR, 



A VERY ingenious mechanfc says, 

 he has discovered new powers in 

 water, by whicli he can work a steam- 

 engine at one-tenth of its present ex- 

 penditure; though every feature of his 

 supposed invention has been tried 

 over and over again, above twenty 

 years ago, and failed, from being 

 upon mistaken principles. 



He says, he discovered in a steam- 

 boat on the Mississippi, that steam at 

 a high pressure is comparatively 

 cold; and tiiat experiments have 

 been now made, wliich tend to ex- 

 plain the cause of this phenomenon. 

 I desire to tell him, that this fact was 

 universally known among the scien- 

 tific in London twenty-five years ago, 

 and probably long before that time.* 



He tells us too, that, by throwing 

 high-pressuro steam into another 

 boiler, we can save nine-tenths of the 

 coal which this boiler would other- 

 wise consume ; in reply to this, I 

 say, that fifteen years since, myself 

 and my family, put up a boiler on 

 purpose to try this experiment on a 

 large scale ; and it totally failed, by 

 consuming one-third more coal, tiian 

 if it had been burnt under the working 

 boiler in the usual way ; and I have 

 since seen it tried by several others, 

 with equal success. He next talks 

 of condensing under the pressure of 

 70lbs. to the inch, when the most that 

 can by any possibility be gained, by 

 condensation, is 14lbs. He there- 

 fore confesses a loss of 56lb3. besides 

 the mistake from the fact, that ten 

 times his pressure would not condense 

 three atoms of steam ; he also sup- 

 poses that ho crams the interstices 

 between the particles of water, in 

 his full boiler, with caloric, so full, 

 he says, that steam cannot have 

 room to generate, and therefore there 

 is no steam until the water is in its 

 passage to the cylinder ; now, I never 

 knew water escape from a boiler 

 but it retained its character of water; 

 or steam, but it inclined to become 

 water. 



I will endeavour to stale my senti- 

 ments upon the nature of steam, and the 

 more, as it will assist to (;xplain my 

 argument : water, separated inlo parts, 

 becomes steam; separated still further, 

 it bi^comes gas ; and the operation still 

 pursued, the gas becomes divided into 



its 



• The true cause was explained m our 

 labt. 



