SOD 



Jug up from the land about them. Thefe forts of drains 

 were formerly much in ufe, and thought highly of in fome 

 diftrifls and places, mod likely on account of their cheap- 

 nefs ; but they are now fallen into negleft and difrepute, 

 probably in confequence of their want of fecurity and dura- 

 bility, efpecially in lands which are under the plough. 

 They are, however, ftill made ufe of occafionally on paf- 

 tiire and fward lands in fome fituations. The methods of 

 making them differ in different cafes and circumflanccs, ac- 

 cording to the nature and kinds of land, being in fume in- 

 ftances formed with much more folidity than in others, as 

 may be feen under the articles SuRFACE-Drains and Drain- 

 ing. They can perhaps, on the whole, be fcldom had re- 

 courfe to with propriety, except in cafes where other kinds 

 of more folid materials are procured with great difficulty. 



SoD-Fence, any fort of fence which is conllruftcd of 

 materials of this nature, either for inclofing land or de- 

 fending it againft the waters of rivers or the fea. See 

 Fences. 



Thefe kinds of fences, when made againft the fea or large 

 rivers, fhould have a good degree of flope, as two, three, or 

 four feet, to one in height, according as the cafe may be. 

 i They have in fome dillricls, as in Lancafhire, in many in- 

 ilances, a bafe of about forty feet, and flope upwards in 

 the direftion of the fea as well as that of the land. The 

 extent of bafe is, however, different in different places, as 

 well as that of the flope or flopes. Fences of this nature 

 againft the fea in the above county, coft about 3/. the rod 

 of eight yards in their conftruftion. 



SoD-Kiln, any fort of kiln which is built or conftrufted 

 with fods, for the purpofe of burning lime or any other 

 material t)f that kind. They are very common in fome 

 places. See Kiln. 



A very clofe fort of fmothering heat is produced in this 

 way, which readily conve'-ts any calcareous matters into 

 lime of a good quality for u'e on land. 



Sou-Knife, Drainhig, an implement of the knife kind, 

 which ;.^ made ulc of with great advantage in fcoring and 

 cutting out the fwavJ or graffy furface in forming drains. 

 It is a verj ulcful tool, performing the work in a neat 

 manner. 



SODA. See Sodium. 



Soda, in the Materia Medica. Muriate of Soda. See 

 Muriate of Soda, Salt, and S-ivlts. It is obferved, (fee 

 Thornton's Chemillry, cited by Mr. A. T. Thomfon in the 

 London Difpenlatory,) that the common fait of commerce 

 contains fmall portions of muriate of magnefia, muriate of 

 lime, and lulphate of lime ; and for the feparation of thefe, 

 the fait is to be diffolved in tour times its weight of pure 

 water, and into the hltercd folution muft be dropped firft 

 muriate of barytes, and then fubcarbonate of foda, as long 

 as any precipitate falls. Then filter and evaporate the clear 

 fluid flowly till the fait cryftallizes, which is pure muriate 

 of foda. This pure muriate of foda is inodorous ; its tafte 

 it ItriAly fait ; and, when pure, perfeftly devoid of any 

 degree of bitternefs. It is in regular cubes, which are not 

 affedled by expofure to the atmofphcre. When it deli- 

 quefces, it contains muriate of magnefia. It'; cryftals de- 

 crepitate when heated ; and in a red heat melt, lofing about 

 tvio per cent, of their weight ; and in a ftill greater heat the 

 fait is volatilized, undecompofed, in white fumes. Its fpecilic 

 gravity is 2.126. It is equally foluble in cold and in iiot 

 water, nearly three parts of either being required to diliolve 

 one of fait. It confifts, according to Kirwan, of 38.88 

 of acid, 53.00 foda, and 8.12 water in 100 parts. It is 

 decompoicd by fulphuric acid and nitric acid. 



As an article of the Materia Medica, this fait is tonic 

 and anthelmintic in moderate dofcs ; purgative in larger ; 



SOD 



and externally ftimulant. In the ordinary mode of ufing 

 it, the tonic power of fait operates in afiifting the procefs of 

 diijeftion ; and, confequently, taken more freely, it proves 

 ufeful in dyfpepfia, and in corretting the weakened ilate 

 of the inteftines, which favours the propagation of worms. 

 In large dofes it is faid to check vomiting of blood, and 

 may be ufcd as a purgative ; although it is feldom em- 

 ployed. But the purgative quality of fca-water does not 

 altogether depend on this fait, as it contains a much 

 larger proportion of muriate of magnefia, which is alio 

 purgative. Asa local llimulant, its folution in tepid water, 

 in the proportion of ^fs or 3] to qj of water, forms the 

 common domefUc enema. It is ufed alio as a fomentation 

 to fprains and bruifes ; and diffolved in a large proportion 

 of water, forms the belt ftimulant general bath, whether 

 ufed cold, or in a tepid, or a hot ftate. 



With a view to the firft intentions, the dofe of muriate of 

 foda may be from grs. x to 3j ; but to operate by ftool 

 from Jfs to 7J is neceflary, largely diluted. 



The officinal preparations of this fait are as follow ; viz. 

 " dried muriate of foda," which is prepared, according to the 

 Dub. Ph., by taking any quantity of muriate of foda, 

 and roafting it over the fire in an iron veffel, (lightly co- 

 vered, until it ceafe to decrepitate, occafionally agitating. 

 According to Kirwan, 100 parts of cryftallized munate 

 of foda contain 8.12 of water, which are nearly diflipated 

 by the heat, and the fait is thus rendered of a more uniform 

 ftrength. It is chiefly employed for the diftillation of Mu- 

 riatic ^dd, (fee that article,) which is obtained colourlefs 

 from the dried fait. 



Muriatic acid of the Lond. Ph. is prepared by firft mixing 

 lilb. of fulphuric acid with half a pint of diftilled water in 

 a glafs retort, and when the mixture is cold, adding to it 

 2lbE. of muriate of foda dried : then pouring a pint of the 

 water into the receiver, and having fitted to it the retort 

 placed in a fand-bath, diilil over the muriatic acid into this 

 water, with a heat gradually raifcd, until the retort becomes 

 red-hot. The fpecific gravity of muriatic acid is to that of 

 diltillcd water as 1.170 to i.ooo. If apiece of limeftonebe 

 immerfed in a fluid-ounce of it, diluted with water, the 

 quantity diffolved ought to be half an ounce. The Edinb. 

 Ph. direfts the muriatic acid tv be prepared by firit expofing 

 2lbs. of muriate of foda in a pot to a red heat for a fhort 

 time, and when it is cold, putting it into a retort ; then 

 pouring 16 oz. of fulphuric acid, mixed with lib. of water, 

 and cooled, upon the muriate of foda ; and finally diflilling 

 from a fand-bath with a moderate fire, as long as any acid 

 comes over. The fpecific gravity of this acid is to that of 

 diftilled water as 1.170 to i.ooo. According to the Dubl. 

 Ph. 61bs. of fulphuric acid are diluted with the fame quan- 

 tity of water ; and after it is cold, it is added gradually to 

 61bs. of muriate of foda, dried and put into a glafs retort ; 

 and then the liquor is diftilled until the refiduum becomes 

 dry. The fpecific gravity of this acid is to that of diftilled 

 water as 1. 170 to i.ooo. 



This acid, for a farther account of which fee Mi;ri.\tic 

 j^cid, is tonic and antilcptic. It has been ufcd with effeA 

 in typhus fevers, and in fome cutaneous eruption?. It is a 

 common and ufeful addition to gargles, in the proportion of 

 from fjfs to fjij in f^vj of any fluid, in ulcerated fore- 

 throats and cancrum oris ; and in a very highly diluted 

 ifatc, Itlviij in f_^iv of water, it has been recommended as an 

 injeftion in gonorrlura. It has alio been regarded as an 

 antidote in general lyphilitic aflertions ; but tliis opinion has 

 been fliewn by Mr. Pearfon to be erroneous: neverthelefs, 

 by its lalutary effed on the ftomach and general health, it is 

 cap.ible of ameliorating the appearance of venereal ulcers, 

 and of rcftraining for a time the progrcfs of the difeafe, 



when 



