550 PHILOSOPHICAL TRANSACTIONS. [aNNO I67I. 



Next he distils the sea water ; in which work the furnace takes up little room, 

 and is so made, that with a very little wood or coal he can distil 24 pots of 

 water in a day: For the cooling of which, he has this new invention, that in- 

 stead of making the worm pass through a vessel full of water, as is the ordinary 

 practice, he makes it pass through one hole, made on purpose out of the ship, 

 and to enter in again through another : So that the water of the sea performs 

 the cooling part : By which means he saves the room, which the common re- 

 frigerium would take up ; as also the labour of changing the water, when the 

 worm has heated it. He then adds filtration, thereby perfectly to correct the 

 malignity of the water. This filtration is made by means of a peculiar earth, 

 which he mixes and stirs with the distilled water, and at length suffers to settle 

 at the bottom. Paris, Feb. 22, 1670. 



A7i Extract of another Letter ivritten hy the same, concerning two 

 Experiments 7nade for finding another Passage of the Urine, besides 

 the hiown one. N° 67, p. 2049- 



Having been not long since employed in searching after the passage of the 

 urine * in animals, I made for that purpose a dog drink a quantity of water, 

 and thereupon caused his ureters to be well tied about, and emptied his bladder. 

 After two hours I found the bladder empty, and the ureters were not tumid 

 above the ligature. Surprised at that, I believed that the cause might consist 

 in the too much cooling of the inward parts, that had all this while been ex- 

 posed to the air ; the section having been made crosswise in the usual manner. 

 To avoid this inconvenience, I repeated the experiment on another dog, by 

 causing a small opening to be made on each side, sufficient to find and to tie 

 the ureters, and to squeeze the urine out of the bladder, by pressing it with 



Whether the distillation bemade after Dr. Lind's method, or with the more simple contrivance of Dr. 

 Irving, the operator should be careful not to continue the process too long, but to stop when tliree- 

 fourths or only two-thirds of the water shall have been distilled j as the water which is obtained af- 

 terwards is less pure, and the brine sometimes becomes so strong as to corrode the copper-boiler. 

 [It appears from the Bishop of LlandafF's experinaents (see his Chemical Essays before quoted) that 

 tlie water distilled from salt water is not wholly free from saline particles; but tliat it probably con- 

 tains them in so small a proportion as not to injure its salubrity in any sensible degree.] When too 

 much fire is employed it is possible, especially towards the end of the operation, tliat some muriatic 

 acid may be disengaged, the action of which upon the metallic vessels it must be desirable to pre- 

 vent. This might perhaps be effected by adding some potash to the sea water, before the distillation 

 is begun. This important subject has at various times occupied tlie attention of many ingenious 

 persons, (several of them members of the Royal Society) as will be seen when we proceed to the ] 7th, 

 4-8th, 50th, and 62d. vols, of these Transactions. 



* See N° 65, p. 526. 



