/3-NAPHTHOL. 869 



all the horse dung, to disinfect the premises, and to plant afresh in new 

 dung. 



141. y8-Naphthol, C^„H-OH. — Preparation. — To obtain ^-naph- 

 thol from naphthalene it is necessary first to prepare the sodium salt 

 of y8-naphthalene sulphonic acid. It is prepared by heating together 

 equal parts of naphthalene and sulphuric acid at 200° C. The mixture 

 is run into water. The liquid obtained is treated with lime, boiled, and 

 filtered. The lime salt is converted into a soda salt by the addition of 

 carbonate of soda, filtering, and evaporating the liquid to a suitable con- 

 centration. The crystals formed are separated from the mother liquor 

 by centrifuging, and melted with 2 parts of caustic soda and the 

 water required to fuse the mixture. The temperature is raised gradu- 

 ally to 300^ C. When the reaction is finished the product is dissolved 

 in water, hydrochloric acid added, and the precipitated /?-naphthol 

 collected on a filter. 



Properties.— ^-naphthol crystallizes in white lamelte ; it melts 

 at 122° C, and boils at 286° C. It is but little soluble in water, but 

 is soluble in alcohol and alkalies. It is antiseptic. 



Action on Plants. — Soluble ;8-naphthoI, in the form of its 

 sodic salt, burns the leaves ; the insoluble salts, on the other hand, 

 such as those of copper, iron, and lime, are not poisonous to 

 plants. 



Action on Fungi. — According to Mangin a solution of naphtholate 

 of soda, 1 in 10,000, kills the spores of Bremia lactucce (lettuce mildew) 

 and Heterosjjorium echinulatitm (fairy ring of carnations), but it is 

 without action on those of Nectria cinnabar Ina (coral spot disease), 

 Peronospora arborescens, and Uromyces avicidarics. 



Use. — ;8-naphthol is. rarely used alone, but with soapy water, or in 

 the form of a soluble salt. 



li-Naphtholate of Soda. — 144 grammes of y8-naphthol are beaten up 

 with hot water and caustic soda lye added to complete solution (100 

 grammes of caustic soda of 44° B.). 



fi-Naphtholate of Lime. — To .]■ gallon of a 5 per cent solution of 

 naphtholate of soda ^ gallon of milk of lime is added, containing 1 lb. 

 of lime. This bouillie is recommended hy Mangin as a substitute for 

 lime for coating fruit trees. 



P-Naphtholate of Copper. — 4 lb. of /3-naphthol are dissolved in 3 

 gallons of hot water, containing 0-3 gallons of caustic soda of 36° B. ; 

 2^ lb. of blue vitriol in o gallons of water are then added whilst stirring, 

 and the whole made up to 100 gallons of bouillie. This contains 

 naphtholate of copper, with great adherence, which does not injure 

 the leaves (Mangin). 



^-Naphtholate of Iron. — This bouillie is made like the preceding, 

 replacing the blue vitriol by 2-7 lb. of green vitriol. 



Peronospora viticola, De By. (vine mildew). — Dufour tried naphtho- 

 late of soda against this disease without success. Mangin, however, 

 recommends a solution of naphtholate of soda, to w^hich a little potato 

 starch [farina] has been added, so as to distinguish the spots treated. 

 Naphtholate of copper would be equally fit to combat mildew. The 

 soda bouillie decomposes on the leaves under the influence of the car- 



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