o 2 nc 6 h 4 conhch 2 co 2 h has also been examined other compounds of this type but of differing chain lengths so that rings of varying size are believed to form include the following n 4 nitrobenzoyl b alanine o 2 nc 6 h 5 c 6 h 4 conhch 2 ch 2 co 2 h n p nitrobenzoyl 6 aminocaproic acid o 2 nc 6 h 4 conh ch 2 5 co 2 h instead of single rings such as are present in benzene or biphenyl fused rings such as are found in naphthalene can be reacted in form aroyl compounds additional compounds whose salts have been evaluated include the following gamma oxo 1 napthalenebutyric acid c 10 h 7 coch 2 ch 2 co 2 h gamma oxo 2 naphthalenebutyric acid c 10 h 7 coch 2 ch 2 co 2 h gamma oxo 1 pyrenebutyric acid c 16 h 9 coch 2 ch 2 co 2 h the study of the physical chemistry of the lattice modifiers which i have discussed before also has added greatly to an understanding of these systems that is because as i have already noted the modifiers closely resemble the side chains attached to the aryl groups of the prime sensing salts it is believed that the chain of the modifier forms a ring structure in which an alkali metal carbon bonds to an equivalent of the keto group of benzoylpropionic acid because of their structural similarity discoveries in one system assist in the understanding of the other among the acids which have been evaluated as 6 member formers are malonic acid ho 2 cch 2 co 2 h and tartronic acid ho 2.