Decejibee 9, 1898.] 



SCIENCE. 



837 



blight, but later the surface of the bark was 

 found to be thickly dotted with the pycnidia of 

 Sphssropsis. 



On visiting the f chard, which comprised 

 about five acres, ,vas found that the blight had 

 been quite noticeable in 1897. In all cases 

 noticed when once attacked the entire growth 

 of the season had been killed, and in a few in- 

 stances the disease had extended into the pre- 

 vious season's growth. The dead twigs varied 

 from a few inches o a oot or more in length. 

 But few twigs of ae current season's growth 

 were found to be attacked. The growth of the 

 disease on the twigs is determinate, a definite 

 constriction usually separating the dead from 

 the living wood. A few miniature canker spots 

 were found on the smaller limbs, but none were 

 noticed on the larger limbs, as is usually the 

 case. The trees were generally in good condi- 

 tion, and the black rot of the fruit was not spe- 

 cially abundant. 



Some pear trees in a door yard about twenty- 

 five rods distant from the orchard were found 

 to be dying. The top of one tree had been en- 

 tirely removed, while the other trees were a 

 half or two-thirds dead. These trees were also 

 found to be attacked by a Sphceropsis, the 

 pycnidia being very abundant on the dead 

 bark. The spread of the disease was from the 

 top downward, a distinct boundary separating 

 the dead from the living wood. A few black 

 shrivelled pears were still attached to some of 

 the dead branches. 



A Sphseropsis was also found on the twigs of 

 some quince trees that grew by the side of the 

 pear trees. The injury in this case was slight. 



At a later date a canker was found on some 

 quince trees in the Experiment Station orchard. 

 Here the appearance of the cankers and their 

 effect was much the same as on apple trees. 

 Pycnidia of a Sphseropsis were abundant where 

 the fungus was in active growth. The disease 

 was also found to be abundant in alarge qunice 

 orchard, in the vicinity of Geneva, where it has 

 done a considerable amount of damage. 



Cultures of the Sphssropsis were made from 

 the twigs of the three different host plants, and 

 fruits of the apple, pear and quince were in- 

 oculated with material from each of the three 

 series of cultures. Sphseropsis malorum, Peck, 



was produced in each case, while check fruits> 



punctured but not inoculated, remained sound. 



Geneva, N. Y. W. Paddock. 



SCIENTIFIC LITERATURE. 

 Lehrhuch der anorganischen Chemie. Von Peo- 



FESSOR Dr. H. Erdmann in Halle, mit 276 



Abbildungen und vier farbigen Tafeln. 



Braunschweig, Vieweg. 1898. Pp. 756. 



Professor Erdmann has taken the Gorup- 

 Besanez textbook (1876) as a foundation, but 

 has so changed, improved and modernized the 

 work that it may fairly be considered entirely 

 new. 



The printing and illustrations are admirable ; 

 particular attention is called to the beautiful 

 colored plates of the spectra of various ele- 

 ments, including argon and helium, which show 

 a wonderful delicacy of tone. 



In an introduction of eighty pages the author 

 discusses chemical theory, temperature, gases, 

 atomic and molecular weights, and similar 

 topics. The remainder of the book is chiefly 

 descriptive, yet modern theory is introduced 

 when needed. The striking features of the 

 book are its thoroughness, its completeness, and 

 the particular attention given to technical 

 methods, preparation and experiment. As to 

 thoroughness and completeness the reviewer 

 has not succeeded in detecting the omission of 

 a single fact of importance in inorganic chem- 

 istry, which could suitably find place in a book 

 of the size and which was mentioned in chem- 

 ical journals before 1898. 



As to technical methods a few examples 

 must suffice. It is generally known that mujh 

 or most of the chlorine now made is by electrol- 

 ysis of aqueous potassium chloride ; but that 

 chlorine is technically obtained as by product 

 in the electrolysis of zinc from zinc chloride, 

 magnesium from caruallite and sodium from 

 salt, will be new to many, as will be the manu- 

 facture of hydrochloric acid on a large scale 

 from magnesium chloride and steam : MgCl2 + 

 HjO = MgO + 2HC1. If we turn to magne- 

 sium chloride we learn that, in addition to its 

 use for hydrochloric acid and (as carnallite) for 

 magnesium, 15,000-20,000 tons are yearly ex- 

 ported from Stassfurt to be used in cotton fac- 

 tories instead of oil, as concentrated magnesium 



