298 
Machines for Irrigation . 
[Ocr, 
3. To separate the alumina, boil on the residuum sulphuric acid, diluted with 
thrice its weight of water : this will dissolve the whole of it, and leave the silex un- 
touched. 
4. Evaporate the muriatic solution at a gentle heat; when nearly dry, pour upon 
it about half a pint of well boiled distilled water, transfer the whole to ajar or 
flask, and keep it closely stopped for twenty-four hours : if any precipitate forms, 
it is phosphate of iron, which may be separated as usual. 
5. Drop sulphuric acid into the solution ; the lime, if any, will precipitate as a 
sulphate ; separate and calcine at a low red heat, and by the scale of equivalents, 
the quantity of carbonate of lime may be known. 
6. Precipitate the solution by one of caustic soda ; filter, wash, calcine, and 
weigh the residuum, which consists of the mingled oxydes of iron and manganese. 
7- Digest these in nitric acid, with a gentle heat ; allow it to remain exposed to 
the air till nearly dry, calcine again at a red heat, stirring it often, and weigh it : 
if any increase of weight has taken place, oxygen has been absorbed, and this must 
be allowed for in the results. 
8. To separate the oxydes of manganese and iron, boil them in a solution of mu- 
riate of ammonia, with a little sugar; the whole of the manganese will be dissolved 
and the iron left, (it has been ascertained by independent experiment, that no oxyde 
of iron is taken up, prussiate of potass will satisfy the chemist, that it is manganese •.) 
precipitate the manganese, by water of ammonia, cautiously added, and filter ; if 
the liquid has any colour, a portion of the oxyde has been re-dissolved by the excess 
of ammonia, and will precipitate on allowing it to evaporate ; when the liquor is 
perfectly limpid, the whole has been obtained, and may be collected as usual. This 
is Mr. Faraday’s process for their separation. 
Sir, 
VI . — Machines for Irrigation. 
To the Editor of Gleanings in Science. 
The following extracts from Buchanan’s Mysore, descriptive of the usual modes 
of raising water in that country, and giving data for calculating their respective 
performance, may uot be’ without use to some of the readers of the Gleanings ; and 
will 1 hope draw from your correspondent H. D. E. some further calculations of the 
comparative value of these machines for raising water, and of any others that may 
he commonly used in India. 
The single' Yatam of Buchanan, Dcnkhi, or Denklee of Hindoostan, and Dhap of 
Rungpore, will be familiar to most of your readers, being the commonest means em- 
ployed for raising water in Bengal and Behar, and generally in India, where the 
springs lie near the surface of the ground. The double Yatam of the coast 1 have 
never seen used in Hindoostan* Buchanan’s Capili/ or Puchally may not be very 
easily understood from his description ; it is the common m6t of the Deccan, and 
not met with, that I have observed, north of the Nerbuddali ; 1 consider it a great 
improvement upon the mot of Upper India, and I shall he happy if I make it better 
known. 
The advantages of the Deccan m6t over ours, are, that it requires the attendance 
of only one man, that it raises more water, and discharges the whole that is brought 
tip; and the wear and tear of the bag is much less. The mot of our provinces requires 
the attendance of two men ; one to drive the bullocks, the other to pull in and emp- 
ty the bag. The Deccan mot is entirely managed bv one man, who drives the bul- 
locks ; the bag empties itself, and the general introduction, therefore, of it into our 
north-western and central provinces, would save one person’s labour at each of the 
many thousand wells constantly working for seven months in the year. Our bag is 
small, and still it is a difficult matter to discharge its contents, a large proportion of 
which is always lost, and a considerable delay attends the emptying of it ; the bullocks 
either not lifting the bag high enough, or pulling too far and strong. But by the con- 
trivance to the Deccan m6t> of the second bag or tail, to which is attached a separate 
rope, that draws over a rollerat the top of the well, the bag empties itself, and must 
be entirely discharged by the time the bullocks have completed their pull; and with- 
out any loss of water. The rope from the tail of the m6t is attached to the lower 
bar ol rather a deep yoke, that the tail may be pulled in nearly on a level with the 
surface ot the inclined plane on which the bullocks walk; and iu consequence of the 
